I had this with my ex, he used to watch porn all the time, made me feel so crap!! In the end he just lied about it, it ruined my trust for him, ruined our relationship. In my experience he won't stop , he will just hide it. You can either accept it or move on. I could accept a guy watching it occasionally, i know quite a few girls who would but the amount my ex watched I just couldn't. Guess its up to you and what you thinks acceptable... I guess I learnt though that it didn't mean my ex loved me any less, it didn't mean he didn't care it's just something he liked to do. Good luck xx