Miles is the Bad Guy

[ColoredButtholeFlaps]

After multiple viewings one thing I've come to realize is that Miles is actually the bad influence. I hope that he changed as a person by the end. There is hope for that and that he stays committed to the relationship with Mia.

Points
It was found out that Miles cheated on his previous wife. Not sure if the wife ever found out, but probably moved the divorce further.
Jack was cheating, but he wasn't married, so while a jerk move, not necessarily against the religion he converted to.
I also believe this was Jack's first time cheating and he wasn't the serial philanderer he was made out to me. Just the way he fell in love with Stephanie and how everything was different to him. he would have experienced that feeling with anyone he cheated with.
Obvious - Miles stealing money from his mom

[FeministLikes2SuckD]

This is definitely Miles' movie and I think he is the one that undergoes an arc. I do hope it becomes a better person in the future and develops a relationship with Mia. However one comment he made to Mia after she found out Jack is getting married is that he tries to separate himself from Jack and says he just knows him as his college roommate. When in fact they seem to be good friends throughout after college with Jack even remaining friends with his ex-wife and Jack knowing about his relationship deeply, and foibles that led to the divorce. That tells me that they speak on a regular basis. Maybe he grows, but it still might light occasionally.