This is actually based on the question that coachTanthony recently asked as well as a reply I saw on it that happens to be very true, and the reply was actually written by a guy. So I give coachTanthony credit because he asks great questions, and I would give the other guy credit but he was anonymous so... oh well.
With this take, by "biologically reversed gender roles," I'm referring to the facts that 1) women as a whole are trying to become more dominant and make men submissive and 2) men as a whole are becoming more insecure.
First I want to point out that a lot of this comes from my culture and how I was raised. Usually in our culture in Latin America the men are dominant and the women are submissive. (This DOES NOT mean sexually. It's referring to society in general.)
Biologically speaking, men are meant to be the dominant ones. That doesn't mean that a man has to make all of the money or do all of the supporting, and in present times that's actually impossible unless he's working all of the time and never at home (only to be complained about by the woman because she thinks he's cheating or avoiding the family) or he's a rich guy. Both have to support each other in every way.
On the women's side, there are the men who will get you pregnant then leave, and honestly that's a big reason we end up with feminist kids (a topic for another day). There is no reason for men to do this because if you don't want the woman 100% then don't have sex with her.
HOWEVER, fellow women, if you give your 50% and you wanna tango with him too, then when he leaves and you're pregnant then you can't complain. You did that to yourself (unless he led you on: see below). I know I'll get a lot of disagreement from my own gender here, but really, if somebody doesn't want to be with you the rest of their life, you can't force them, and having sex definitely won't be forceful enough. If anything, it'll make matters worse when you get pregnant. (Why have a baby with somebody whom you're not gonna spend your lifetime with?) And I am also against abortion... just throwing that out there. With all of this said, guys should not lead a woman to believe he wants her completely just to get sex. This is where the problem comes in.
I can't even say one gender is the guilty one for "love you and leave you" because obviously men do it a lot but so do women, and honestly I am extremely guilty of it myself (not including sex).
Men shouldn't judge themselves based on how women see them. And yes, I'm referencing this only to men... Don't judge yourself the same way women do, because in all honesty and truth, if you're not an alpha then you're gonna mess up your own confidence. Obviously (here is where I take women's side) alphas are not the only ones who have girlfriends. Are they still more successful with getting women, though? Sure. That's biology. A lot of guys like to push this off and claim that what makes an alpha is money, fame, etc., and for a lot of women (gold-diggers) it's true, but it's not true for our majority. For us, what really makes a guy an alpha is his view of himself and his confidence. Yes, we pay attention to how YOU judge YOURSELF.
On the other side of that coin, biologically we women do tend to judge ourselves based on men's opinion of us. I'm not saying it's a 100% good thing, but if you don't believe it or disagree then go out on the town and count how many women you see who don't wear make-up. That's just one example. I will say that it is much better if a woman judges herself by her own standards and not by a man's as well.
But overall, for men to be the dominant ones, they should judge themselves by their own confident standards. If a woman you like doesn't like your standards (a.k.a. you don't meet hers) then she's not good for you anyway. It's the same the other way too, for women. To both genders: you shouldn't change for anybody (unless it's a matter of improving yourself FOR YOURSELF - like fixing a cursing habit, for example); you should be yourself because if you change for everybody you want then you're never going to be the same person and therefore you'll never be yourself.
As for rejection, everybody is a hypocrite on this one. There is no other explanation. When one person (of either gender) expects the people they reject to just go on about their own business like it never happened, they still do the same emotional things to the ones that they want. It's hypocritical. I'm extremely guilty of this too. We all need to expect to receive what we give, and if we don't like it then we shouldn't give it.
So in conclusion, really both genders are at fault, but I do believe that society has given us (everybody) a reasonable excuse. I think it has hurt it's own self.