There's no gaslighting going on there, buddy. Josy told you in the beginning she was involved with somebody. Maya was a bit less forthcoming, but neither of them had any reason whatsoever to suspect you knew the other, there was no real deceit going on with that aspect of it.
MC over-reacted like a bitch snowflake. Yes, he's justified in being upset, but not to that extent. Especially if you consider how much potential there is for him to have been dipping his stick elsewhere the whole time. Derek was right to call him out for it, too.
Having been fortunate enough to
socialize with a couple girls who shared a dorm room, I wasn't bothered in the slightest.