Well, it's certainly implicated in that decision. If MC fucks Helen (which is the choice you make), Harold won't come back and Mia will be disappointed, because MC failed his promise to help her. So much is clear and I don't think that's pointless at all.
Else it's not really about MC, but about all other characters. The game gets somewhat boring if every girl/women - more so mothers and daughters - in the game is willing to share at will. That's neither realistic nor really that much fun. And sure, in the end it's not about realism but at least for me there are certain points where it gets harder to immerse.
You forget about one thing. If we choose Mia, then Harold comes back for the daughter's good, but he does not make himself happy. So we have a happy daughter and parents who are together, but they are really strangers to each other.
If we choose Helen, then Harold decides to follow his heart and try to create a happy relationship with his colleague.
The choice itself is a strong simplification of the situation, because the real choice is made by Harold himself and not by MC. Why? Because Harold does not know about the night rituals of MC and Helen. So their relationship has no right to influence his decision.
At this moment, the story of Helen and Mia is illogical and full of holes like a sieve.
There are many illogical and unbelievable things here.
1. In such a small environment, it is impossible to hide so many MC's relationships with different women. So DarkCookie will have to find an explanation for why women will accept massively that they are only one of many women in MC's life.
2. The fact that the teacher at school also make a massive relationship with the student is also unbelievable because it is against the law.
3. Most of women do not care about contraception and even want MC to go inside. A child is a serious matter, so the possibility that all women are so willing to get pregnant is also unbelievable.
In order for the whole story in the SS to make sense, DarkCookie will have to present some credible reason why so many women of all ages are willing to have an intimate relationship with MC and are ready to share it with other women and why each of them wants to get pregnant.
If DarkCookie finds the right and reasonable explanation, the fact that MC fucks "half" of the town and that all his women will give him permission will cease to be unbelievable.
All you need is a good explanation.