I've always been kind of confused by how people describe emotional cheating. I'm not sure if that's because people are vague about their opinions, or if I just view it differently enough to where it's difficult for me to understand their perspectives.

I don't really get how people form a sort of romantic/sexual bond without romantic/sexual interaction. Like, you can have a crush on someone who has a crush on you, but how is that cheating if you don't do anything about it?

I'm my mind, emotional cheating is having a romantic/sexual-esque relationship with someone other than your partner without doing any explicitly sexual activities.

What is your opinion? Bonus points if you include how you developed your opinion.