I predict that Prez will graduate and get with Nurse, then Riri will be brokenhearted. It can go either: Riri slowly starts to appreciate Uda then gets with her, or; Riri only sees Uda as friend, they both get brokenhearted.
Either makes sense, I trust in the author to respect everyone's feelings and not contrive romance out of air if Riri gets with Uda, that is, Uda shouldn't just be mere rebound, Riri only goes for her if she truly sees Uda as lover.