We love to watch porn together. He used to hide it from me until he found out that I like it as much as he does. I grew up with a bunch of brothers and found out a long time ago that guys/porn/masturbation all go hand in hand. Why your guy needs to keep it private could be for alot of reasons,, he's uncomfortable sharing that with a girl or he just may like having something he does on his own. Don't feel threatened unless his sex time with you diminshes b/c of it.