My (18f) best friend/roommate's (18f) bf doesn't want our guy friends to stay in our house. He's a huge jerk but I don't want to cause problems.

So I live in an apartment with one of my best friends, lets call her Rebecca, in our college town. She has been with her bf since high school, but they were very on and off because honestly the guy sucks. I'll call him Rocket (19m). None of us like him because he's not a very good boyfriend and he's very controlling. He lives in the same college town as us. For halloween, I invited a bunch of our friends from home to come visit, offering them our place to stay and my roommates said they were ok with it. Some of those friends are guys and one them specifically has some history with Rebecca. They never dated or were serious, just went out a couple times. Rocket hates this guy, let's call him Fernando(18m). There's been multiple situations where he picks a fight with Rebecca just because she's in the same place he is. He told her he doesn't want him to stay in her apartment, even though he'll be in a different room. I feel really bad for Fernando because he's a really close friend of mine and he's always caught up in these situations where Rocket makes a big deal about him just being there and he also doesn't want to make anyone uncomfortable. Rebecca tried to talk to Rocket about it and he was very upset about it and saying that she wouldn't like it if his ex stayed in his house and how he doesn't like that Fernando keeps coming to hangouts and stuff. (??? we've all been good friends before Rocket came into the picture. ) He said he wasn't ok with ANY of the guys staying there and that everyone knows he doesn't like Fernando. I really don't want them fighting because of something I did or cause problems between them, but Rocket is always blowing things out of proportion and wanting people to do what he wants. I really don't know what to do because I don't want to cause problems between them but I really wanted to see my friends. Rebecca said she might just stay at his house for that weekend, but this is literally her apartment too. Is there any solution here? I'm just really tired of this guy always wanting to control what she does because there's been so many situations where he gets mad at her for not doing what he wants but I don't want their relationship problems to be my fault even though we both wanna spend time with our friends.