And I am sure there will be many Whedon fans who are bitterly disappointed. The fansite Whedonesque has already shut down. And I can understand all that. His actions certainly were those of a hypocrite, and there are many people who are disappointed.
However, I think adultery is an entirely separate issue from your political stance on feminism. I don’t know if Whedon also set himself up as paragon of faithfulness, if faithfulness was something that was a major issue for him. That would be a different matter. But feminism is mainly about the fact that women and men are equals. This belief really doesn’t have anything to do with unfaithfulness (which happens in all kinds of constellations, in relationships between two men or two women, or in male/female relationships from both sides), although there is certainly an overlap especially when it comes to how society treats unfaithfulness by men and by women.
But in the end, that’s where this ends for me: cheating on your wife is a huge private failure for Whedon, but not one that in any way impacts his writing or his political views for me. And the public at large won’t care for this one bit. I do feel sorry for those fans of his to whom his personal virtues were important, but that’s not the kind of relationship I have with a writer, nor do most people, I believe.
One caveat: if it turned out he abused a position of power over actresses, all of this would be a different matter.