And really, Ritsu didn’t have any good reason to reject Ami like that. So, he must’ve been entertaining the Uta path for a long time without realizing it, and his piss-poor excuse for fake-dating seems like the “only option” only for him.
Uta on the other hand probably already legit felt like that, but committed to never spilling the beans until he showed interest in her. I’m assuming that’s her thought process.
So, in retrospect, they were both degenerates all along. Cute ones though.