Sarah Michelle Gellar Calls Freddie Prinze Jr. Her 'Favorite Husband' as She Celebrates 18th Anniversary

Sarah Michelle Gellar has a sweet message for Freddie Prinze Jr. on the 18th anniversary of their wedding.

The Buffy the Vampire Slayer alum, 43, celebrated the big milestone on Tuesday by sharing two photos from their nuptials.

"You... are my favorite husband," she wrote in the caption on her Instagram. "#happyanniversary."

Gellar and Prinze Jr. — who first met on the set of the 1997 thriller I Know What You Did Last Summer — married on Sept 1, 2002. The couple share two children: daughter Charlotte Grace, 10, and son Rocky James, 8.

Earlier this year, Gellar and Prinze Jr., 44, celebrated the 20-year anniversary of their first date.

“20 years ago this week, my friend @realfreddieprinze and I were supposed to have dinner with a mutual friend from out of town,” the actress wrote in February. “That friend missed her flight, but we decided to still meet and catch up.”

The actress continued, “Now 20 years together, 17 plus married and two kids, we still go to that restaurant for dinner. So thank you @sloaney77for not showing up for dinner.”

In March, the parents spoke to PEOPLE about their decades-long love story and how they each knew they had found the one after that fateful dinner.

"We were friends for a very long time. We've had many dinners before. We were supposed to go with someone else, and that a third person didn't make it out and we decided to still go," Gellar recalled. "We were just two people at dinner catching up. We had a long car ride and a long dinner, and things just happened."

Though the two "didn't believe" in marriage at the time, Prinze Jr. said that he didn't want to be with other women following that date.

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"I didn't go on dates with other girls nor did I even want to pursue dates with other girls," he shared. "One day, I just knew we're going to get married and that I was going to propose. I didn't know when or how."

"Fortunately, she was on the same page and my instincts were correct," the actor added with a laugh. "We're together because we like each other. We make each other laugh."

As for the secret to their successful marriage, Gellar told PEOPLE in 2016 that the key is to pay attention to one's partner.

“Take the 10 minutes – put the phone down. Have a cup of coffee together. Walk the dog at the end of the night. Read a story with your kids,” she said. “Make the most of the time that you have. We are all pulled in so many directions, so make sure that, whichever one you are focusing on, you’re present.”