Why are pedophiles normalized in manga?

Might have to drop this bc of the romance, I hate when authors make mentally adult people marry/fall in love with children… I rly was enjoying this too, it had a strong plot and interesting characters. But of course there had to be an annoying obsessed child falling head over heels for the mentally adult mc:( I was super excited bc there seemed to be no romance in this, and even tho he doesn't seem to actually love the little girl right now, we all know by the time they're teens he, an adult, is gonna fall in love with her…