@Harambe each girl has some self-serving reason for being into the mc, fmc was in it for the money, Ruka needs the drama to feel alive, and Mami was a controlling bitch, that could not accept losing a loser, especially to a paid escort. New girl is into a ton otaku shit, has a rotating list of waifu/husbandos, and probably decided to jump on mc's D, when she discovered he's a real life dense harem protag.