Does this guy just not get boners?
I don't know how dicks work so...
I don't think it's really about that, he says it actually works down there. It's more a problem of simply not feeling it and in the end not really seeing the point of sex. Guys and girls can have the same issue. A lot of girls (more than we think) can't feel anything during sex, sometimes it can be "cured" (like when you try with a particular partner) and sometimes you can't.
GAH thoes moments when Kuroo just fucking SNAPS!!! Just *growns and make weird noises* I need a towel (⊙…⊙ )