Unfortunately getting together without telling your brother would be a bad idea as he would inevitably find out and ****storm.The best thing to do would be to speak candidly to this guy asking him what he plans to do about that and whether or not he has the balls to ask your brother about dating you Once you've consulted with your brother, it's ultimately your choice and your life.
Sometimes I catch him staring at me in a non-platonic way when I'm doing something, or we'll touch (whilst playing a game etc) and the room will fill with sexual tension.
He's asked me twice whether or not I have a boyfriend, to which I've responded that I've not got anything going on at the moment.
But the problem is, the longer we don't do anything about it, the more the sexual tension builds up?
I know my brother would NEVER accept a relationship between me and him.
Let's look at it this way, if I could choose any guy to be my sisters boyfriend/husband, I would choose my best mate, because I know that he's a great guy and he would treat my sister with great care. But if your brother knows that his mate plays around with girls and treats girls with little respect, then he has a right to feel angry about the situation, because he's only trying to protect you.