18+ Netorare Manga no Kuzu Otoko ni Tensei shita Hazu ga Heroine ga Yottekuru Ken

I suddenly realized: I had been reincarnated as the scumbag whose role is to steal away the heroine of this ero-manga universe. Well, that's not to my taste, so I figured let the heroine get along with the protagonist. Or so I thought... Heroine, why are you paying so much attention to me!

(Source: Square Enix, translated)