My question is this: Should the man in a relationship ALWAYS have to foot the bill? Or should the bill be somehow split, whether 50/50 or 80/20?
That's between you and your partner/date/etc. My personality is that I never assume someone is going to pay for things I want (therefor, I do not expect it); nor do I invite people to events that I expect them to pay for. If I invite - I expect to pay for others unless it's known that everyone is covering their own before-hand. If I'm tagging along - I don't expect to have things paid for by others (though I usually confirm whether or not payment is expected before any expense is made).
P.S. - We're both 20 year old college students.
There are several ways I would have handled this (with varying degrees of hostility).
First - she's a grown-ass woman. If she's going to hand money to people, she needs to handle her own affairs and make sure that she communicates her expectations regarding that money. She can't get upset when she hands her daughter, going to an event with a guy as a couple, and the money gets used--
Second -- as a couple. You two are going as a couple, and as adults - are more than capable of making decisions on your own. You're supposed to be looking after and taking care of each other. That's what friends do... especially boyfriends and girlfriends.
Third - your girlfriend is an adult and can choose to use the resources she's given how she sees fit. If she felt it was appropriate to pay to get you home - that's her prerogative. That's then a dispute between her and her mother.
The fact is that if you two are serious about each other - then your parents are going to have to understand that you're a couple. You aren't just "you" for your parents - she's an inclusive part of your life. She isn't just "her" for her parents - you're an inclusive part of her life. The longer they try to pretend that is not the case, the harder life is going to be for them and you two (until you two have the means to sever financial and other reliances with them).