so you want him to turn into his biological father
but nah I hard disagree would make no sense not just from a relationship stand point but also would make alot of the choices meaningless and pointless to that the branching the way it is if it just turns into a harem. It would make the game worst just to appease people that want to be greedy.
However I would not be against a bad ending where he is a cheating son of a bitch if you manage to not get caught till the end. Then they find out about it and he ends up alone and homeless from them taking everything he has from a divorce and his mother refuses to help him.