When we were younger and He still lived with his parents, I just accepted then that he'd be watching stuff--I watched porn. But when we moved in together, I felt a little unhappy about the idea of him looking at other girls and becoming aroused. Much of the time we have lived together, I have been home when he is, so I'd feel unhappy knowing that he was doing that with lonely me in another room...
Neither of us care for the typical porn star aesthetic. If I did catch him watching a cheesy porn with tanned, false-breasted, heavily made-up girls, I would feel like I didn't know him. If I caught a porn trail of a different kind, I'd tolerate a little. But if I noticed there was a trend with girls who were anatomically very different from me, I might feel very, very insecure.
I think the closest to porn he touches now is manga with some sexual content. Unless he's sneaking in lots of sexing 2D girls, I don't care too much. I believe his favorites often involve girls who simply pet each other and blush.
We don't watch porn together. We tried that years ago and I think we agreed it wasn't our thing.