Another issue I have with story at this point is how 2 out of the 4 main girls are effectively poorly fleshed out in term of character development, frankly the 3 girls that are the most fleshed out in the game are Alice, Leah & Hailey, Mel & Karina are actually not properly fleshed out and frankly each of them would have needed one arc to properly flesh out to make the fact they are options at the end to go solo with make sense.
Now here is the deal Alice is obviously the best fleshed out girl of all, she has been there from the start and you had some crisis to resolve with her, so frankly the notion you wouldn't end with her is pretty ridiculous all things considered, you have a stronger relationship with her than anyone else short of Aunt Hailey. Now Leah you helped her thru 2 crisis, first the Susan crisis than the be the pretend not so pretend boyfriend for the parents to meet, those helped fleshing her out and creating stronger emotional ties with her, now she is really close bound to Alice, pretty much in love actually, frankly one of the ending options if anything should have been Alice & Leah + the MC, as it would have been far more sensible an option to being solo with either Mel or Karina. Next you have Aunt Hailey, well you had 3 different crisis involving her, first your uncle's death, your secret relationship with Alice, and last her house being broken in, all those actually fleshed her out very well and even if she appeared late in the story made her a significantly more fleshed out character to anyone short of Alice, she should have absolutely been a ending option, far more than Karina or Mel at this point.
As for Karina & Mel, the problem is each lacked a deeper emotional attachment form from a crisis, neither of those girls were in a dramatic situation that the MC helped solve, Karina is a young inexperienced minx, while she seem to be growing at the end in love with the MC it feel like their is little in term of emotional development on the part of the MC to really justify that pairing only with her, a crisis would have absolutely helped providing the root for a stronger relationship that could have made that option work, for example her parents discovering he is dating both daughters, now that would have created a nice little explosion that could have by its resolved time helped create some strong ties between Karina & the MC, it could also have led to another stronger crisis on Leah's part as well fleshing her out to the level of Alice & Hailey, possibly having Leah reveal she is dating a girl as well.
Also for Mel really except the fact she is crazy exhibitionist druggie, she also isn't really fleshed out all that much again their isn't really any significant emotional development to properly tie her up to the MC, she would have needed a crisis of her own to make her work as solo option really, something like discovering that Mel's mom is suffering from a disease, so its why she seemingly is never around to work at the Coffee Shop with the MC, or the shop is endangered and the shop might close, now either way or Hell both ways could have helped the MC form some strong ties to Mel that would have justified having a solo ending with her, otherwise it doesn't really make sense.
Now currently with what we have in term of character emotional development, frankly the ending options should rather be this: Alice Solo, Alice & Leah, Aunt Hailey or Harem. Frankly Karina & Mel aren't fleshed up enough as is to have their own ending, the only ending that make sense is with them in the Harem, nothing else really make sense. Now Alice Solo would work fine due to the fact she is one of the two most fleshed out characters in the story, similarly ending with Aunt Hailey Solo would actually sort of made sense, if things went that way you could have Alice & Leah being together on their own and it would have made things pretty nice at the end too. Now the Alice & Leah + MC is the best option frankly if you don't want to go Harem, because Alice & Leah were already dating and close together before the MC came in the picture, they basically had him join their relationship, so it make sense that in the long term the three stick together, more than Alice Solo frankly, and I don't think Leah Solo really make sense compared to Alice & Leah being with the MC. Obviously you than have the Harem option, which would be for the MC to keep all the girls, including Hailey, also possibly with a side of Susan, I mean seriously its the dream of every guys on Earth to have a Harem, so the notion the MC wouldn't entertain that idea above all is a bit out of character.
The Break Up option actually feel more like that fourth option they added to Mass Effect 3, you know the fuck you all for complaining the assholes at Bioware & EA gave us, WHY would you ever chose that option? After an entire story of character development and emotional development, with a freaking Harem possibility, why chose Break Up? The only way the Break Up option would make sense is if the Harem ending wasn't possible, so the MC could chose to chose no one to avoid turning the girls against each others, he decide to effectively break up with all of them, but you know still sleep with them time to time without committing to a relationship with any of them.
So yea the current ending selection need a significant redo if more character development isn't going to be added, if a character emotional development arc isn't added for Karina & Mel they need to be removed for options to go Solo, and frankly the notion the MC would go Leah Solo and not Alice & Leah is crazy, so yea that needs to be changed. As I said Alice, Alice & Leah, Aunt Hailey and the Harem are the only 4 viable ending to the story without more character emotional development for Leah, Karina & Mel, it would require significant development for the last two in particular for them to go Solo with the MC to feel like a satisfactory ending.