This is a GREAT idea ! I loved Roommates and there's so much an expansion could include, like:
1. If you've already completed the game for both Anne and Max, you could intertwine the two: have them talk about their love interests and even go on a double date
2. If the expansion does include a second year, a great way to introduce the new romances could be to have the members of Latin House notice you're all alone and set you up on a blind date
3. Relationship troubles. Nothing major, but as already noticed in these forums, Isabella has been hinted to have a possessive side (even in her non-romantic route). Not necessarily like the jealousy scenes from the original game (felt mildly out of place), but maybe a "You are mine" moment. Disagreements are real and I would like to see how they handle that.
4. Fraternities and other bullies can be BIG trouble; they could be interesting to overcome/understand
5. I DEMAND AND ENDING SING-ALONG