I know what you mean and am sensitive to this behavior also. Franky I can't tolerate it.
I made this clear to my BF right off the bat. I told him I didn't want a BF that oogled other women. My dad did that and it revolts me.
When we are out and I look at my BF, I always catch his eye as he is always keeping one eye on me.
Yah, he is aware of his surroundings. He can see what ever is out there, but glances right past and back to me. I like this - it makes me feel special and cared for. He is aware that respecting me works out to be more rewarding.
I hope your BF will be respectful of your sensitivity.