This is so wrapped up in all those issues on the "what do you consider cheating thread?" and then some.
I agree that it smacks of control. It would seem to me that both guys could appreciate some hot porn without feeling inadquate. However, that doesn't work in all cases -- and especially if there's "baggage" or self-esteem issues, just saying "get over it and watch this with me" isn't cool.
But, it goes beyond that. It seems that your partner is suspicious that you are playing around on the Internet to hook up. If that makes him uncomfortable, you need to address that issue head-on. If you love him, you might want to think about talking this through: what the Internet-play is all about, and what you consider "cheating." I don't think there's a cookie-cutter answer to this. But I know that if I was doing something that really bothered my partner, we would talk it through and come to an understanding. If that understanding meant I was going to stop doing it, I would.
By the way, fratpack, can you package up your avatar and send him to me?
Thanks.