Yes, I know, we've all heard the “what about the menz?” posts one too many times. But, really, the social concept of masculinity ought to be a feminist issue. Let's look at what the masculine man entails.
(1) The man is the financial provider. That means that if his wife out-earns him, he has somehow failed in the performance of masculinity. Therefore, a high-earning female (or any female who desires a career) is “emasculating.”
(2) All men are up for sex at all times, and spend their time thinking about sex. I'm not sure I even need to spell out the problems here. Failure to perform adequately as a (hetero)sexual man is severely stigmatized. Harassment of women is proof of masculinity.
(3) A man is in control of his own life. In my experience this is rarely true of anyone – the only way to control everything in your life is to go be a hermit. This encourages men to try to control those in their lives.
(4) Violence is the natural male response to a perceived threat. Again, should be self-explanatory. Combine with 2 and 3, is it any wonder some men resort to rape and abuse?
(5) Men cannot or should not know how to cook, clean, etc., or if they do they should not enjoy it or do it willingly. A real man should only do housework, childcare, etc. if pressured into it by a woman. Which of course makes her a nagging bitch.
I don't think we can make progress as feminist without addressing the way masculinity is portrayed. Masculinity is portrayed as the opposite of femininity and as having power over women. We need to not only convince women that they have power, but convince men that they can have power in their own lives without putting the women around them down (or for that matter, putting other men around them down).