Jessica777, you have to keep in mind that your boyfriend is only a man. He has eyes and he is going to use them. Face it ... Men look at women and women look at men. Your last boyfriend probably did it, he just wasn't so obvious.
We all have eyes for a reason. If he isn't flirting with the girl or making eye contact and taking it over the line, then I wouldn't worry about it. Let him look because it's purely innocent. If he ever takes it too far, though, then there would be a problem.
Hope things get better for you guys. Take care.