Well, I really wonder why all those people somehow fall in love at first sight and act as if they've been lovers for a hundred years when they've barely met for a day or two. Really. It's especially unreasonable when it comes to modern day people, be they transmigrated, reincarnated or not. They live in a world where porn is everywhere and you can see whoever you want naked(well, not really, but you get the point) including even the smallest parts of whatever part of their bodies you fancy and in whatever way.
Who the fuck would actually fall in love so easily? It's extremely unrealistic even without our internet warrior experience. Just how innocent are these mass-murdering homidical maniacs? People don't just suddenly fall in love like that.