Why is the term ''loser'' applied almost exclusively to men?

Girls don't like dating ''losers'', right? The times I've heard I wouldn't date this guy or that guy because he lives with his parents, doesn't have his own house, doesn't own a car (this is especially big in the US), doesn't have a job or a good job and so on. I have rarely if ever heard a guy call a woman a loser for any reason (including the ones I just mentioned) or refuse to date for because of them. What's up with it?

I think society tends to view a man's success as gauged by his personal achievements, whereas a woman's success is gauged by her partner's achievements. If this is the case, then it makes more sense to call a man a "loser", since he has failed to achieve, whereas a woman often isn't expected to try, or rather, it doesn't impinge their ability to marry a successful person. In other words, "loser" as an insult implicitly attacks a man's self-worth, whereas this isn't so much the case with women. That would be my speculation, at any rate.

But most women don't seem too eager to change certain aspects of gender roles , do they?

I think most women simply want the choice.

They don't seem to want to give men the same choice though. Have cake and eat it.

I don't think that's entirely accurate. I do think most feminists genuinely want men to have choice too - but this doesn't mean they will choose men who make 'feminine' decisions for partners in their relationships.

what the hell is a 'feminine decision', exactly?

I meant to describe decisions which don't conform to a traditionally masculine gender role. For example, wanting to be a house-husband, or behaviour resulting from lack of ambition or want of independence.