see the NTR is in some way justifiable and it makes it far more tolerable (for people like me). the dad fucks the girl MC clearly likes and so he says "so your gonna do me like that just because you cant be bothered to go out and actually find someone. well then i guess im gonna fuck you thing up and your gonna deal with it"
Usually is the other way around. - MC likes girl and she likes him back and then MC's father rapes/blackmails get stealing her from MC. This story is a twisted version of that cliché. - MC's crush always goes to MC home and does house chores, dad teases MC that she might be a good wife for him and MC buys that then at late night MC finds out his own father fucking his crush despite he knew he liked her so he snaps and then blackmails/rapes and steals her from his father. There's a LN version that came with the VN.