Does anyone have an issue with their partner watching porn? Weigh in on both sides please.

This was a disagreement between me and my boyfriend. I won't say who is who.

One of us thinks it's fine watching porn and getting off to it while we are in a relationship (1-3 times a weekish).

The other doesn't watch porn because we are in in a relationship and having their partner getting off to other men having sex/fantasizing bothers them.

It was a big disagreement, what's your take?