So what if the Plat in the couple is female ? And the male non status.
To me it's a "treat" given to a partner. They get a kick out of flying first for the first time whereas to me as the Plat it's just a short hop and I'm not going to get that same thrill so why not let them have a new experience (and I have an easier way of explaining why MRs need to be flown )
Actually though in this case I think the guy is a jerk-it obviously DOES matter to his girlfriend (whether it should or not is another matter and irrelevent) so as he got the upgrade on the way out-how hard would it be to say "If I get upgraded on the way home it's yours"