This is not the first time I've heard of this happening, so it must be a pretty common thing that is happening to a lot of couples. It is strange, but I think there's an easy explanation for it.

What we have right now is known. I'm in a relationship with Ms. Z and I know everything about Ms. Z. If I've explored her personality, we've been intimate for years, etc. etc., there's little left to the imagination or that remains unknown. That's how, I think, a lot of and maybe most guys feel after a time in a relationship.

But when it comes to the movies, or pornography, or other escapes like that (books, etc.), it can be more interesting and exciting because the person is fantasizing and imagining what things might be like with that other person, in some other environment or world. There's no worrying about the daily concerns of a relationship, or really, of worrying about the other person as another human, feeling adult.

Fantasizing and imagination, in the right context under the right conditions, are wonderful, super things to do and be able to do in our lives. But when we choose fantasy over reality, that's when there's a sure sign of trouble. As in your situation. Your boyfriend would rather prefer fantasizing with other women than the real woman in the bed right now. That's probably or could be a symptom of something wrong in the relationship, whether it's not communicating very well, or something.

But it should be a wake-up call or a sign to you that maybe this guy isn't worth your time any longer. Or, if he is, that he'd better get his act together and you two need to talk about this and how badly his behavior makes you feel.

Good luck!
DocJohn