To me, your thread did not appear to be asking if your bf looking at porn was a bad thing, but rather saying that it did indeed bother you. Trust is essential for a relationship to exist. If you feel this way, you are unhappy and to my mind, that is a problem wheter or not porn is objectively good, bad or neutral in a relationship. Have you tried talking to him about it? Telling him how you feel? Communication and trust go hand in hand- if it's this big secret and you feel ignored and like he's cheating on you than the relationship sounds really miserable and not worth staying in.
Just my two cents worth...