Nectarine at From Anger to Activism has started an interesting thread asking for comments on how committed heterosexual feminists who are partnered with men can be to feminism. I commented there, but thought I'd post it here, too, because I think it's a good question, is important, and I don't want anyone to misunderstand any of my comments here or anywhere else. This is what I said, edited some for clarity.
I think het feminists, partnered with men, can be every bit as committed to feminist causes as unpartnered het feminists or lesbian feminists and sometimes more so. I've met plenty of lesbians who identified as feminists and yet who weren't at all committed, either to feminist causes or to women, that I could see. I've also met plenty of feminist women without partners, male or female, who were pretty noncommittal about many feminist issues and about women, just in general.
I don't think the issue is the sex of your partner– I think the issue, so far as feminist commitment is concerned, is whether or not you are woman-centered. I think you can be woman-centered and yet be partnered with a man. What I also think, though, is that more often than not, your (generic "your") woman-centeredness will cause problems in your relationships with men. There aren't too many men who can really support a committed radical feminist woman, no matter how good their intentions are. Ultimately, that generally becomes evident and you both become increasingly miserable, and then a choice will have to be made, and that can be hell. But again, I don't think the sex of a woman's partner has anything to do with how committed she is as a feminist.