I tend to think there's an aspect of heteronormative stuff running through some of this. Western women, at least, are taught to see male vulnerablity as special, and in need of our nurturing.

"My Nigel, who suffers so beautifully, is a male who can embrace his feminine side and therefore I should feel no guilt for being codependently attached to taking care of my senstive little boy and of seeing other women as unworthy of him. A woman's suffering is a dime a dozen and if she can't deal with it, then she's faking being a damsel in distress, and not the stoic endurer, and she's not worth our effort, because, after all, we're going through the same mundane things and she ought to just take care of herself instead of feeling entitled to being the center of attention."

It's one of the ways the kyriarchy gets women to care more about men than other women, and even ourselves--if not male peers, then male children. I don't think this is the only thing going on here--everything everyone else saying is part of the drive here, but it's one of the strands. It's one of the ways slash is not revolutionary (as opposed to the ways in which it is), but can give a reader normative, or cathartic, satisfaction.