All kinds of crazy situations happen on television, so as a viewer, you have to expected the unexpected.
Just because a character is dead or missing, it doesn't always mean they're gone for good.
Related: 13 Oddball Couples We Never Expected to Love
There's no excuse for cheating, but there are a couple situations where it may not have happened on purpose.
Check out our slideshow below of 11 characters who accidentally cheated on their partners.
June Osborne - The Handmaid's Tale
When June started her love story with Nick, she was under the impression that her husband, Luke, had been killed. She later found out that Luke was still alive and was fighting to find a way to save her.
Robin Hood - Once Upon a Time
Robin's wife may have died, but she didn't say dead. After Robin found love with Regina, Emma altered the timeline by saving Marian's life and bringing her back to Storybrooke.
Jane Villanueva - Jane the Virgin
After Michael's tragic death, Jane eventually moved on with Rafael. But it turns out that Michael wasn't dead after all, and returned to the show with amnesia.
Lori Grimes - The Walking Dead
The zombie apocalypse hit right when Rick was admitted into the hospital. Unable to get him out, Rick's best friend told Lori that Rick was killed. The two ended up starting a romance, so it was a big shock to her when Rick showed up alive and healthy.
Lily van der Woodsen - Gossip Girl
Faking his own death wasn't something we would ever put past Bart Bass, but Lily clearly didn't know what her husband was up to and moved on with Rufus.
Jared Vasquez - Manifest
Jared proposes to his girlfriend Michaela, who leaves to think over the proposal. When her flight doesn't return, Jared waits years before eventually moving on and getting married. But you know the drill. As it turns out, Michaela was alive and hadn't aged a day.