People that cheat.. why do you do it? No judgement, just curious!

I wanted to see if people would be honest about cheating. I want to know why you would or what the situation was..

I recently got cheated on by a guy that I was engaged too and thought we were in love. He's only asked me to marry him a month ago. I truly I'm dumbfounded I don't get why or what happened.

I'm not polling this to pick out the cheaters I'm really wondering why people cheat.

Please no judgements...

Thanks.