I'm a woman, and I certainly don't feel any less "womanly" after getting myself off... nor do I think of my boyfriend as being less "manly" after he masturbates. Like savvypup, I find my bf's masturbation to be sexy, and it's an expression of his sex drive
... likewise for myself.
Gender roles/types would be the last thing on my mind (especially because I don't care much for what society says about them, so I try to ignore notions of "manliness" or "womanliness" since neither I nor my bf fit easily into any of those categories, and we like it that way
).
Here's what goes through my head: "Gee, I'm horny, I want to masturbate," then I do it, and I think, "Ahhh, that felt great."
I don't think, "Shit, I've lost my mojo!"