humans are habitual, many men and women cant climax through penetrative sex with a partner because they have masturbated so long that they get into the habit of only climaxing this way
its just a case of finding out your partners habits and trying to change them
your bf is in the habit of fantasisng about other people/scenarios when he is sexually aroused so if you want the relationship to work and have a healthy sexlife you need to break this habit by getting him to fantasise about you!
Try wearing sexy outfits or roleplaying, (depending what turns him on) and then he may stop wanting to watch these deviant movies and think about you
He may be feeling pressure about the way you have sex, if you like hard fast sex where it doesn't matter if he climaxes after 2 minutes then he may be totally different to if you wanted slow sensual meaningful sex, this is when the majority of men think about other things and people to try and stop themselves climaxing too soon