John Krasinski put his foot down over this surprising Jim-Pam storyline

Fans of "The Office" know the love story between Jim and Pam made us all believe in the concept of happily ever after.

Now imagine if Jim had totally blown it all — by cheating on Pam. That was a storyline the show's show’s creator, Greg Daniels, proposed, but actor John Krasinski, who played Jim, refused to film the scene.

According to cast member Brian Baumgartner’s new tell-all book, "Welcome to Dunder Mifflin: The Ultimate Oral History of The Office," Daniels pitched an idea to have Jim betray Pam, played by Jenna Fischer, while Pam was on maternity leave.

The story Daniels wanted to shoot, which would have happened in the season-eight episode "After Hours," had Jim making out with Cathy (Lindsey Broad), Pam's temporary replacement at Dunder Mifflin, during a work trip in Florida.

Daniels reasoned that the show's writers needed "to inject a bit of upset in the tranquility at that point and try and get the intensity back," he recalls in the book.

But Krasinski heard about the storyline and said no way.

"That’s the only time I remember putting my foot down," Krasinski says in the book. "'Cause (Greg) was saying 'You're going to actually make out with her in this scene.' I remember saying things that I never thought I’d say before, like, ‘I’m not going to shoot it.'"

Krasinski knew he wasn't alone, and that the beloved show's fans didn't want to see Jim cheat on Pam either.

In the book, Krasinski recalls telling Daniels, "'My feeling is there is a threshold with which you can push our audience. They are so dedicated. We have shown such great respect to them.

"But there’s a moment where if you push them too far, they’ll never come back. And I think that if you show Jim cheating, they’ll never come back.'"