Hmmm.
I can only really speak for myself and say that I, as an individual, do feel that I have a responsibility to all women. To those who went before and to those who have yet to come. Maybe that comes from the luxury of knowing that I have a voice, that I have a very privileged position both in my industry and in my economic position and being aware of these positions and the advantages that it gives me, I do feel obliged to use the power (?) that it affords me.
I do think that women shouldn't keep quiet, particularly when it comes to sexual and domestic violence so yes, I do think there's a collective responsibility that feminists have to use their voices and speak out. I know that at my most vulnerable point as a woman I didn't have a voice and still don't over that particular aspect so was overwhelmed and grateful that others spoke for me and that their actions supported me even when it cost them.
Is it a duty ? I don't think I'd go that far but that's primarily because I am aware that not all women can always live by feminist principles nor is it always safe and that doing so can come at great personal costs. But shouldn't we at least examine whether each occasion affords us an opportunity to either set an example or help other women ?
And as for choice, I don't think women will ever have the freedom of choice while we still have the levels of inequality that we do so for me, that's a bit of a moot point.
There has to be more to feminism than just online debate or theory, there has to be real practical application of it because, let's face it, if it isn't us doing it, who will be ?
And I'm sorry if that's all a wee bit idealistic but having seen some of the absolute twattery on here in recent weeks from women hating women, yes, I think feminists need to speak up on behalf of women even if it means taking a bit of heat.
Should the OP stick by her feminist principles in determining her marriage even if it means the end of it ? That's a balancing act and I think there's enough freedom in feminism to allow her to get the balance right. The very fact that she's examining and questioning it all is probably her feminism in action. Just because the outcome might seem to the outside world to be a traditional one doesn't mean that the path to get there hasn't been a feminist one.