And it's never easy. But it doesn't always have to be a sad situation or a bitter memory forever, but rather a great big lesson.
Watch: The science of cheating. Post continues after video.
Unfortunately, cheating on a partner seems to be more of a common theme in relationships than it should be. As such, we reached out to our wider Mamamia community to share their own stories.
Without further ado, here are the 14 most bizarre ways people found out their partner was cheating on them.
'My daughter read his text messages.'
"I had no idea my husband was sleeping with a woman at church until I heard blood-curdling screams after one Sunday service. We'd arrived home and I'd been cleaning out the car when I heard my daughter on the other side of the house. I was by her side in less than 20 seconds but my husband was already there and he was holding my daughter while she sobbed. I was confused, concerned and terrified. Eventually, my daughter belted out, 'You are having sex with [Church Woman]?'
"It then came out that they'd been sleeping together for about nine months, were deeply in love and deeply unhappy in their marriages. My husband and I divorced a few months later and split custody of our daughter. She and her father have done a lot of hard work to get back to a good place. Don't hold any hard feelings against my husband. It's been almost a decade since it happened and he's with the woman he had an affair with, and I am also happy in a relationship."