Yes exactly and then it would be different. If he was a truck driver and wanted to take someone else somewhere then that might be an issue (or not depending why), but when you are promoting something for example you go with who will facilitate that promotion best, be it a film, sponsorship, paid partnership (adv), showmance or just because it's more media interesting for that person to be there and someone else. It's never personal, and shouldn't be taken personally.
At big industry do's half the people rock up have their pics taken and then go straight home or someone else anyway,they are only ever PR do's really, so it's really quite a non event, however my point is to Anonymous to get back to the actual question and stop defending my relationship, don't be a controlling oddity, it won't end well.