John Krasinski is just the bro on the side for Matt Damon

Along with George Clooney and Brad Pitt, Matt Damon and Ben Affleck have one of the most enduring - and adorable - bromances in Hollywood.

But Damon's "Promised Land" screenwriting partner, John Krasinski, seems to be creeping in on that action.

When CNN spoke with "The Office" actor about working with Damon on the upcoming drama's script, Krasinski filled us in on the long hours spent at the Damon home, which was bustling thanks to Damon's four daughters.

"I went to his house every weekend. We were basically moonlighting," Krasinski said of their writing collaboration, which crafted a script about a natural gas salesman who faces tough choices when he arrives in a rural farming community.

"I basically would arrive Saturday at breakfast and work until dinner, and then do it again Sunday," Krasinski went on. "But I'm not sure how we got a lot of work done because these four beautiful girls are everywhere. So between putting in 'Little Mermaid' 17 times and him making lunch and bath time, I don't know how we got work done, but we definitely did."

Once you hear the kind words that Damon has for Krasinski, it could appear that Affleck's in danger of being replaced - but Krasinski's having none of it.

"I can't break up the bromance! I think I'll be thrown into a car and I'll disappear for many, many years," he said. "That's an untouchable one. Especially being a kid from Boston, you don't go anywhere near the Matt and Ben thing. If there is a bromance, I'm sort of like the mistress who's off on the side, and that's not a good place to be, trust me. I don't want that, I'll just let them do their thing."

Damon, meanwhile, joked with CNN that he thought Krasinski was just using him to get to Affleck. "Ben's like the big time A-list director now, so I'm just a stepping stone," he said.

But both actor/filmmakers have come a long way from their "Good Will Hunting Days," although "in one respect, it feels like yesterday," Damon said.

"I mean that was 15 years ago ... And then I look now. we're both married, we have these beautiful children, we've lived a lot of life, and it's been great. I think most people get in their 40s and start having that weird relationship with time where they go, 'Wait a minute, I still feel like I'm 25, but I'm not, and how did I get here?'"