I think theyre doing the story in a nice way so we all get our fanservice and they do it, but he can continue harem'ing with her friends and I bet stepmom and son just give each other a "wink" once in a while haha. Until season 2 when father gets sick and is out of the picture !!
@InfinityNore I agree, but I think this would be like a one time thing, allegedly. Then other women comes up and have relationship with him then she remembers this and how it felt, which in turn makes here jealous making potential drama and the father might get involve. Just a prediction.
@E--JIROU
It won't end until they're all down for a 5-some, or his dad finds out about his being cuckolded by his own NEET son & rightly kicks his ungrateful ass to the curb...