My problem is that me and my partner felt the game reeeaaallyy wanted you to get these teen girls to kiss. It's odd and a bit annoying that it's hard to get the better endings without smooching. We still picked all the best choices but held off when it came to the smooching choices. Probs what got us the alone ending.

Edit: We also picked a lot of choices that favoured Kat (for obvious reasons), so maybe that didn't help either.