Most of the harem members will stay as they're. Catherine's (a thirsty widow who MC took as a lover) daughter will get impregnated by MC without MC knowing (she tricked him) and her son will kill MC to get the throne and make his own mother to be his lover. Yes, Catherine's son want to be a king and kill his own father so that he can fuck his own mother. MC's son become like that because he deemed MC neglected his mother who's very lonely and thus he decides to comfort his own mother loneliness, by sex, of course.
As a king, he can kill people who opposed him from making his own mother as a sex slave. Catherine as a mother obviously refused her own blood-related son to be his lover, but as a thirsty woman who many times almost cheated on MC because he's away for wars, she can't refuse her own son from making her his lover. She's very honest to her lust for sex.
Oh yeah, Catherine's son also wants to impregnate his own sister but MC unknowingly impregnated her first. Oh well, there will be another chance because he's a king anyway lol.
After MC got attacked by his son, he got turned into a vampire by Lucy. After that he will say goodbyes to his women and this is when Catherine tell MC that she can't reject her son to make her his lover because she need male genital to fill her female genital. Yes, she's that thirsty.
Then MC will woke up in the future like how I described in my earlier comment about Sci-fi.