My boyfriend thinks I'm TOO CLOSE with my brother?

No, it's perfectly fine your boyfriend is a controlling idiot, he's trying to isolate you from your family so he can eventually unleash his internal monster. I'm not kidding. I say in a years time he'll be long gone, your brother is there for life. Ignore your boyfriend and go see your brother. You guys are close, he'd do anything for you, including protect you from that . And if your boyfriend cares about you he would WANT you to go see him, and he'll be happy and waiting when you get back. If not, well that says a lot.