Glenn Howerton Wasn’t Happy About Rob McElhenney Dating Kaitlin Olson—Here’s the Wild Backstory

If you’ve ever lived with your best friend, you know things can get weird. But It’s Always Sunny in Philadelphia star Glenn Howerton took weird to a whole new level when he found out his roommate Rob McElhenney was secretly dating their co-star Kaitlin Olson.

And no, he didn’t take the news well.

A Litter Box and a Secret Romance

Howerton, who plays Dennis on the long-running FX comedy, told Variety the story. He was literally scooping cat poop when McElhenney broke the news.

Resale Prices for Christopher Nolan’s ‘The Odyssey’ Tickets Are Already Skyrocketing

“I thought he was doing a bit,” Glenn said. “Because he knows that the stupidest thing you could possibly do is date your co-star.”

He wasn’t wrong. Relationships can get messy. And when your entire show relies on chemistry between friends, romance can throw everything off. One bad breakup and boom—your show’s toast.

Victoria Silvstedt, 50, Stuns in Bikini During Rare French Riviera Outing

So, Glenn freaked out.

“I was like, ‘You idiot! You’ve got to be f—ing kidding me. You know this is the stupidest possible thing you could be doing, right?’”

But Rob wasn’t kidding. He was all in. He told Glenn they had both tried to stop it, but it was too strong. “We’re in love,” he said.

Tracy Spiridakos and Jesse Lee Soffer Spark Dating Buzz with Sweet Italy Snap

Hiding It From the Gang

They tried to keep it quiet. No one on set knew at first. Even Charlie Day, their co-star, had no clue. And he was already married to Mary Elizabeth Ellis—who’s played “The Waitress” for years.

But Danny DeVito, who plays Frank, picked up on it. He said he noticed something shifting. The two were just naturally gravitating toward each other.

“Every once in a while, people who are supposed to be together wind up together,” Danny said. Classic DeVito.

Still, Glenn was in the dark. Even though Olson kept “crashing” at their apartment after supposedly getting too drunk.

“She wasn’t really that drunk,” Glenn said. “She was just using that as an excuse to stay over. And Rob would disappear for a couple nights, and I’d be like, ‘What’s going on?’ He’d tell me he went out with some girl… just making s— up!”

Love Actually Worked Out

So, was it a disaster? Nope. It turned out to be the best thing.

Rob and Kaitlin married in 2008. They’ve now got two teenage sons and have kept their relationship going strong—on and off screen. That’s a rare thing in Hollywood.

And the show? Still going strong too.

In 2021, It’s Always Sunny in Philadelphia became the longest-running live-action sitcom in American TV history. Not too shabby for a crew that started off as three broke guys shooting videos with a camcorder.

It’s kind of sweet, really. A sitcom about selfish, messed-up people led to a real-life love story. Even if it did start with some very bad lies and a cat litter scoop.