Unless you have saves for individual girls and Lizzie/Vanessa, Anastasia/Cecile (probably okay to add Daphne/Amber/Nichole into that mix - as casual sex) it'll probably be a messy end where you're left with just the side characters and none of Lizzie/Venessa/Amiee/Brandy/Stephania/Jeane.
May get away with Amiee/Jeane as they're related - but then they don't like cheats. I kept as save for those two plus Lizzie/Venessa/Amiee & Lizzie/Venessa/Amiee/Jeane just in case.
I'm not sure why a bunch of people think there's still a harem (or harem-ish) possibility with this game. We were basically clued in way back at the party, when at certain times you have to choose a specific girl. You couldn't choose Stephania
and Amie, and you had to decide one girl to sit next to / flirt with during the movie. We've been told for a long time, explicitly, that there will be certain combinations that won't work, and we've already seen the first of those when Nichole tells us to choose between her and Brandy.
If you weren't able to see this coming, you've haven't been paying attention. If you haven't been saving at critical branches as you go along . . .
. . . I guess you'll either end sad or you'll replay several times to see each separate ending.
BTW, it's nice to see that Jeane's relationship is still -86. Somehow she still talks to Brian, though.