Whats the science behind posting gay online? I love anime femboys but would never EVER fuck a real man irl btw. There are enough STD catchers in the world, and I'm not exactly pining to be next up for such a badge of shame.

It's possible that you're just not allowing yourself to be attracted to real men and so your brain is fixating on the next best thing which is anime femboys. I fixated on flat chested women for most of my life until I realized I was gay.
Try watching gay porn and telling yourself it's not gross or wrong and see if you can get off to it. Also try imagining yourself being physically affectionate with other men and see how you feel.
I think the vast majority is just a girl with a dick slapped on. The picture you posted is an actual hipless skinny twink body though.