What's going to happen when he runs out of the product? Think his girlfriend will simply leave him? I'm willing to bet no, and I'm also willing to bet his girlfriend might not be so keen on having been "gotten" by a cologne and would likely report other reasons for dating him. Think someone is going to get involved with someone just because they like their particular brand of BO?
Come on: think critically.
Synthetic aids to pheremone production or sense, if they are truly to work as pheremones do, should be doing nothing more than essentially making your own natiural smell more obvious, something that could be done by say, not wearing deoderant or bathing less, rather than giving a smart capitalist your bucks.
If these are doing anything else, or if they smell like something that isn't your body odor, than what you're essentially looking at is the same thing as using a cologne with a scent someone likes.