it makes sense for swing to find interesting/passionate (i think this is the right word for this context) women attractive, so long as he can get a reaction out of them, he will continue to bug them U_U I see him making it his life's mission to annoy/scare/fluster a shy girl by harassing/stalking her because of the reactions she would give him. perhaps this would also draw him to more mentally unstable women, as they're less consistent in their actions/identity/etc and have more impulsive behaviors, which he would find interesting? heh a yuu who's especially depressed, manic, or just lonely would probably entice him
as for the physical section, of course I agree. it's a given. a good pair of thick thighs could draw his attention in any situation U_U
Swing stalking mentally unstable girls to drive them to the brink of madness is exactly the kind of thing he’d do.
Maybe someone who shares his ideals would be the perfect match for him.
Even so, I can totally see him being with a normal girl as long as she’s not too passive and loves him just the way he is.
And as for Yuu... Well, aside from the fact that he seems to be after her because she knows about Christmas and could ruin his holiday, her canonical attitude (as reflected in the game's responses) is ultimately exactly what Swing is looking for.
(Even though I refer to Yuu as a girl, they can be whatever gender you want)