If you and her planning to have sex, then only watch, else the 2 of you will be consume with lust and will feel very uncomfortable if you don't proceed to release.... in bed...
I watch together with my boyfriend, but sometimes it gets very boring because porn stars can get very unrealistic with what they're doing.. My boyfriend loves porn though...
I occasionally watch hentai. I won't lie. I think most people with internet access do watch porn sometimes, although some won't admit it.