rnch saidif your long term bf followed you around the room with his eyes, smiling the whole time, briefly glancing away to talk to other people or to check out a cute guy...would you get uptight/upset at his staring at you?
Well in all fairness aren't you doing the same thing if you notice that his eyes are constantly following you and you happen to be watching when his eyes divert to check out other guys? Sorta double-edged there.
I'm trying to figure out where the "gay" behavior fits into this. He's your BF so the fact that he's watching shouldn't come as a surprise plus he's smiling which is better then him have some ice cold stare of death on his face. if anything you should be flattered. It would be different if he was a complete stranger doing this. That would be creepy.
If he's your bf then confront him about it if it makes you feel uncomfortable.