It's difficult to phrase a judgment because you're complicit but technically NTA. Your boyfriend is
Look, he shouldn't be springing your presence on his roommate when it sounds like the two of them share a bedspace and that's it (i.e. there's no common room.) Because it does put pressure on the roommate to plan his schedule around your visit. (Like when he got kicked out of his room).
Roommates should have an agreement in place BEFORE bringing guests over, particularly for overnight stays. It's called being an adult and communicating/compromising. The emphasis is on before. Not now. Your boyfriend screwed up.
That being said, this isn't exactly your fault. It is on your boyfriend, but you are participating in this