In the end of the day, you are human. Film is a job which is not an individual job; you have tons and tons of people behind you - you have a whole crew of people working. But, an actor is the face of a film, so you get all of the good things, but you get the bad things, also.
I've never cheated or been cheated upon. I've seen my parents together and secure. So I feel the same way. Infidelity stems from low self-esteem. You want to cheat when you don't feel good about yourself.