Is looking at porn a form of cheating?

I know that you can set your own standards of what is and isnt cheating in a relationship. for example: some people are okay with their partner flirting or what not while others are not. Anyway, I am uncomfortable with my man looking at porn. It's not that I am insecure, but I am still young and always willing to have sex when he wants it. i should still be turning him on. we have been together 3 years and in our first month he would still try to watch porn with me but we talked about it and i wasnt comfortable with it so there was no more of that and nothing more was said about it. in the last year and a half we have had less sex, on average now we have sex maybe 4 times a month. im always up for sex whenever and even try but nothing changes.weve had talks about it and still, nothing changes. he hasnt looked at porn or anything in this time, but then a month ago he told me hes interested in us getting pornos and him getting porn and whatnot. this was out of nowhere. it upset me because i didnt know all this time thats how he felt, and it also upset me since i am trying to turn him on like with lingerie and stuff and nothing amuses him. but then he wants to look at other girls? is that the only way he will have sex with me or something? plus when we do have sex he its usually quick just enough for him to get off. thats it. i just dont like porn at all and wish he would see it upsets me. i should be good enough. dont men get to see enough women naked/half naked on movies and tv enough? do they really need the porn too? shouldnt he respect how i feel about it? i dont understand....i dont need to look at other guys to be turned on by him.