What makes husbands jealous?

My husband and I have a great marriage, but sometimes I feel like he takes me for granted. I know he would never stray, but I still feel a little possessive over him. I trust him and don't ever prevent him from doing whatever he wants, but I still hate the idea of other women showing an interest in my man, even if he would never notice it himself. I want him to trust me and feel secure in our relationship, I do, but it would still be nice to feel like he was at least a tiny little bit possessive over me. He doesn't care if other men look at me or think about me. Once a guy even grabbed my breasts at a club (in front of him) and he didn't do anything, even though it was it was against my will. He doesn't give it a second thought if I meet guy friends without him. Still, I'm attractive, I get attention and I could easily find another man if I wanted to. Of course I would never, since I love my man and we have kids. But does his lack of possessiveness/jealousy mean that he doesn't care? Should I worry? Would anything make a husband like mine jealous or is it just that he thinks noone would ever give ME a second thought?