If he's really sleeping with this woman and still wants Riko... wtf this is so wrong

Well, I'm pretty sure he doesn't see Riko sexually, it's just an obsession in which he needs her in his life...kinda like siscon
So it's not like he wants to date Riko but he sleep around, he just has sexual urges and he fulfils them with random women, none of them are as important to him as Riko, so he doesn't care about any of them, he just needs her to stay by his side. It is a bit unfair tho, since it's obvious that he wouldn't allow her to date if he had his way, yet he doesn't see her as a love interest

Now I understand what's going on