David Foster and Katharine McPhee's Relationship Timeline

David Foster and Katharine McPhee are a musical match.

They first met on American Idol in 2006 when McPhee was a contestant and Foster was a guest mentor. They became friends — Foster even played the piano at McPhee's first wedding — and it was seemingly all platonic until rumors about a romantic turn began to fly in 2017.

Foster and McPhee made their red carpet debut as a couple in 2018 and tied the knot a year later. They welcomed a son, Rennie David, in 2021.

The Grammy-winning producer has embraced fatherhood again — he has five daughters from previous relationships — saying that "it's just great being a dad," while McPhee has referred to motherhood as the "greatest job" she will ever have.

From their first meeting on TV to days out with their son, here's everything to know about David Foster and Katharine McPhee's relationship.

2006: David Foster and Katharine McPhee first meet on American Idol

Foster and McPhee have known each other since 2006 when McPhee was a contestant on American Idol. Foster was a guest mentor on the show and worked with McPhee, who later finished as runner-up, as she prepared to sing Whitney Houston's "I Have Nothing," a song Foster co-wrote.

After they met, Foster told cameras that McPhee had a "great, great future ahead of her." Fellow guest mentor Andrea Bocelli said, "You have to say also, she's nice, beautiful and young," to which Foster nodded and laughed.

February 2, 2008: David Foster plays piano at Katharine McPhee's wedding to Nick Cokas

In 2008, McPhee married actor and producer Nick Cokas at Beverly Hills Presbyterian Church, where Foster was in attendance. He played piano to accompany McPhee as she sang Natalie Cole and Nat King Cole's "Unforgettable."

September 19, 2017: David Foster and Katharine McPhee appear together at gala

McPhee separated from Cokas in 2014 and the divorce was finalized in 2016, while Foster's marriage to his ex-wife Yolanda Hadid ended in 2017.

That same year, Foster and McPhee were seen in public together a number of times, including at the Grammy Museum's third annual gala, sparking dating rumors. However, a source told PEOPLE that they were "absolutely not dating."

November 6, 2017: David Foster and Katharine McPhee have a night out together

After attending a Los Angeles Lakers game the previous night, Foster and McPhee were seen hanging out again in West Hollywood, California.

November 22, 2017: Katharine Foster addresses rumors she's dating David Foster

McPhee addressed rumors that she and Foster were dating with PEOPLE, saying, "Here's how I look at it: I'm not doing anything wrong, so whether people think it's true or false … there's nothing bad happening in my life, so people can just say whatever they want."

November 30, 2017: David Foster and Katharine McPhee are seen kissing in L.A.

PEOPLE reported that Foster and McPhee were seen kissing after having lunch together in Beverly Hills, California. The pair then met up that evening at an event at the Stephen Webster U.S. flagship boutique.

The same month, McPhee told Health that she and Foster have been "very close friends" for a while and said that she was "really, really fond" of him.

She continued, "I've known him since I was 21 years old, you know? He produced my first single. So he's been really good to me. People can say whatever they want."

May 7, 2018: David Foster and Katharine McPhee make their red carpet debut

McPhee and Foster confirmed their relationship when they made their red carpet debut at the 2018 Met Gala — and McPhee told Entertainment Tonight that they were having a "fun date night."

July 2018: David Foster and Katharine McPhee get engaged

While on vacation in Italy, Foster proposed to McPhee. "He did it at the top of this mountain in Anacapri. Totally dark, only stars. Thankfully he didn't push me off the cliff. He said it was one or the other. And in the end he spared me," joked McPhee.

A few weeks later, McPhee shared a selfie showing off her engagement ring and paid tribute to her father Daniel McPhee, who had died shortly after her engagement was announced.

"My dad was so happy for me. My ring was the last thing I showed my dad before he passed and makes me smile when I look at this as a reminder of our last conversation," she wrote. "And now I'm ready to share with all of you what has been my sunshine amongst this painful loss … So today we're celebrating life and not forgetting love. ❤️."

September 9, 2018: David Foster and Katharine McPhee perform together at Celebrity Fight Night

At Celebrity Fight Night in 2018, McPhee sang Elvis Presley's "Can't Help Falling In Love" with Bocelli, and Foster accompanied on piano. The charity "marathon" benefitted the Muhammad Ali Parkinson Center.

"A few years ago I told you she was the one," Bocelli told Foster before their performance, with Foster replying, "You were right."

June 28, 2019: David Foster and Katharine McPhee get married in London

A year after announcing their engagement, Foster and McPhee got married at the Church of Saint Yeghiche in South Kensington, London. Among the 150 guests were Foster's five daughters, as well as other family and friends.

McPhee wore a wedding gown by Zac Posen, who was also in attendance, and Foster wore a tuxedo by Stefano Ricci.

December 31, 2019: Katharine McPhee performs at stepdaughter Erin Foster's wedding

The newlyweds attended the New Year's Eve wedding of Foster's daughter Erin to businessman Simon Tikhman in 2019. During the reception, McPhee serenaded the couple and their guests.

June 28, 2020: David Foster and Katharine McPhee celebrate their first anniversary

To mark their first wedding anniversary, McPhee shared a tribute to Foster on Instagram. "A year ago today I married the love of my life. Thank you for always loving me and inspiring me in all aspects of my life," she wrote. "I love you. Here's to the future!"

Foster also marked the occasion by sharing a photo with his wife. "Happy anniversary to the love of my life!!" he wrote.

July 1, 2020: David Foster and his daughters discuss his marriage to Katharine McPhee

In an interview with PEOPLE, Foster and his daughters spoke about his marriage. Though the Foster girls said they had no issue with the 35-year age gap between the couple, Erin joked, "I have an issue with how hot she is!" Her sisters chimed in, joking that their husbands enjoy it when she comes over.

In the same interview, Foster said of critics, "Haters are always going to be haters."

October 6, 2020: David Foster and Katharine McPhee go on a double date with Prince Harry and Meghan Markle

Among Foster and McPhee's friends are Prince Harry and Meghan Markle. The foursome met up for a double date in Montecito, California, enjoying a three-hour dinner at Lucky's Steakhouse.

McPhee and Markle attended the same school as teenagers, and the pair reconnected in 2019.

October 8, 2020: David Foster and Katharine McPhee are expecting their first baby

In October 2020, sources confirmed to PEOPLE that the couple were expecting their first child together.

The next day, McPhee referenced her pregnancy news on Instagram after she received a gift box from Italian apéritif brand Aperol. "Thank you … I won't be drinking this anytime soon — wink, wink — but I'm very excited," she said.

February 21, 2021: David Foster and Katharine McPhee welcome son Rennie David

They welcomed their first child together and Foster's first son, Rennie David, in February 2021. McPhee's rep confirmed the news to PEOPLE, saying that the couple "welcomed a beautiful baby boy" and that "Mom, Dad and son are all doing wonderfully."

The next month, McPhee revealed her son's name on Today. "One of [David's] sisters suggested an old family name," she explained. "It was his great-grandfather's name, his great-uncle's name, so it has a long history in his family. My husband said, 'Hi, Ren Foster,' and so we said, 'That's a good name. It's a strong name.' "

March 2021: Katharine McPhee discusses her age gap with David Foster

On an episode of Dr. Berlin's Informed Pregnancy Podcast, McPhee shared that she was initially hesitant about dating Foster due to the public perception of their 35-year age gap, but that it was never an issue for her personally.

"We all have the ability to label things and to look at something for the way that it looks or face value and make a judgment," she said. "So I totally get the judgment initially, but things are never as they appear, things are never exactly as they appear and I'm in love with our love story and that's all that matters."

August 31, 2021: Katharine McPhee shares a photo of David Foster with their son

Though they are frequent social media users, Foster and McPhee prefer to keep son Rennie out of the public eye. However, the Smash star shared a photo of her 6-month-old son with his father on a plane.

"My boys 🇨🇦🥰❤️," she wrote.

September 2021: David Foster and Katharine McPhee appear on The Masked Singer together

Foster and McPhee joined the sixth season of The Masked Singer together under the stage name Banana Split. The duo performed songs by artists like The Chicks, Lady Gaga and Michael Bublé during their time on the show, but the couple were sent home the week before the final.

December 29, 2021: Katharine McPhee defends David Foster on Instagram

Foster posted a picture of McPhee in a bikini on Instagram with the caption "what baby!" He then faced criticism for perpetuating an unrealistic goal for new parents by commenting on McPhee's post-baby body. The American Idol alum then posted another photo and came to his defense.

"I'm sorry but we are not sorry," she wrote on Instagram. "People freaking out about what my husband captioned seriously get a life ... Stop being so offended by what people post who have zero impact on your life and move on."

April 17, 2022: David Foster and Katharine McPhee celebrate Easter with their son

The couple celebrated Easter Sunday with family in 2022. McPhee shared photos on Instagram, writing, "Pink dresses, Easter bunnies, baskets, friends & fam. But most importantly #heisrisen."

In one photo, McPhee wore bunny ears and pushed Rennie in his stroller, while in another, Foster watched over the then-14-month-old playing with balloons.

June 19, 2022: Katharine McPhee pays tribute to David Foster for Father's Day

To mark Father's Day in 2022, McPhee shared a photo of Foster with Rennie — the first time the couple had shown Rennie's face.

She posted a series of photos and wrote, "Happy Father's [Day] to the man @davidfoster who loves me like I could have only dreamed of & who made me complete in life by making me a mommy. I love our little family. I love our big family."

October 27, 2022: Katharine McPhee says she "guilted" David Foster into making a Christmas album

While speaking to PEOPLE about their upcoming Christmas album, McPhee laughed, "I think I guilted David. I said something like, 'It's really crazy I'm married to the greatest producer, basically of our lifetime, and I've only had you record me on a few songs.' Then he said, 'OK, well, why don't we just do a Christmas album?' "

Foster also said recording with McPhee "was easy because she sings so amazing."

He continued, "I got to make the tracks and do things the way I wanted to, then I'd have her come in and plug her vocal in. It was really fun. There were a couple of songs we were talking about that we didn't know whether she could handle or not, but she handled them like a pro."

January 27, 2023: Katharine McPhee talks about having another baby with David Foster

McPhee spoke about the possibility of growing her and Foster's family during an appearance on The Jennifer Hudson Show. "I would love to have another baby, but we'll see," the singer said.

"We're not in any crazy rush, but I hope so," she continued, before adding, "I love being a mom, I really love it."

April 15, 2023: Katharine McPhee and David Foster attend the Breakthrough Prize ceremony in Los Angeles

The couple attended the Breakthrough Prize ceremony, otherwise known as the "Oscars of Science," at the Academy Museum of Motion Pictures in Los Angeles. McPhee dazzled in a strapless red gown, while Foster looked handsome in a black tuxedo.

November 24, 2023: Katharine McPhee says David Foster's parenting style is "old-fashioned"

While talking with PEOPLE, McPhee and Foster opened up about their differing parenting styles.

"I want to start disciplining [Rennie] and Kat's not really down with that," the composer said. To which McPhee replied: "No, that's not true. I just want to discipline in my own way. There's the more old-fashioned way of disciplining which involves time-outs and things like that. My take is that you can have more mindful parenting opposed to just assuming that a two or three-year-old can have time alone to reflect on what they've done poorly."

McPhee's "new way" of parenting avoids shaming a child for bad behavior.

"It's just a different approach. I think [David's] era of parenting is different than mine. [He's] more results-based," she added. "I think disciplining is something that happens over time."