Yep! I've encountered it in my own life, luckily I have a great relationship with my wife's BFF because they've known each other since they were toddlers.True and sigh I am way past 18 yo unfortunately and learned the hard way that if the woman you want to have a relationship with has a non sexual BFF that she has a deep emotional connection with and you cannot at least connect with that BFF for a relation where you can accept each other to be in that woman's life and act civilized and friendly to each other you better move on since it never works, let alone in a situation like this .......
It makes sense that Alice is the actual main character of this game - she is the face of the game, she is the one who brings everyone together, and she isn't considered to be a freeloader at all when it comes to the whole "freeloading family" bit even though the PC is paying for the privilege to live in the house. Just disappointing that the PC is the extra one in the relationship at the end. Really feels like Alice would be completely happy without him (which is proven by the other endings).
I guess I saw Alice as someone who was experimenting, exploring, trying to decide what she wanted in her life, I didn't see her as someone who was strictly poly and unwilling/unable to have a committed relationship with a single person (of any gender). In the end the idea of the PC being in a relationship with Alice while she is also in a relationship with someone who doesn't like the PC seems awkward and disappointing.