This is just a fan theory - (not even sure if I like it my self but I'm honestly just trying to think of any 'Ramona and Sheldon' scenario that won't involve cheating or relationship crap. They surely can't break up Shamy again)
What if while Amy is at Princeton she meets Ramona. Amy tells Ramona that Sheldon Cooper is her boyfriend and Ramona acts really strangely to this. The nest day Ramona turns up at 4A looking for Sheldon (Amy is still at Princeton). Only Leonard and Penny are there. Sheldon is in the apartment but not in the front room. Ramona remembers L&P and asks if Sheldon is here. She lies and tells them that they have collaborated or he is reviewing something. ( idk I'm no scientist). They call Sheldon who claims he hasn't seen her in 8 years. It turns out that Ramona has been is obsessed with Sheldon and has been stalking him for 8 years and wants her revenge for kicking her out and not sharing credit. Ramona could be a real psychopath and put the lives of Sheldon, Penny and Leonard in danger in some way.
I don't know, it probably trash but any thing is better than some ridiculous out-of-character cheating bs that the writers better not be thinking of doing. BTW I'm new.