you weren't doing enough on your part?
you are who you are and obviously she didn't respect you enough to live with that. you should NEVER have to change who you are to fit someone else
and you can't PUSH someone to cheat, if they truly deep down care about you and your feelings they wouldn't do it. plain and simple. they'd either come to you and say 'hey you know what such and such is really bothering me, we need to find a way to work on this' or just tell you that things aren't working out and it should end.
cheating in any form is a cry that your partner (by that i mean anyone's partner) can't honestly truly deep down want to be in a commited relationship with you.