Interesting question.
I was chit chatting with a woman who had a crush on me, but I was with someone at the time, and her now guyfriend gives her this look every time we embrace. Now, I know she would still like to be involved with me, and she does have a predisposition to cheat, but the hugs she gives me are completely "...damn, Jay, I missed you, hope everything is going well for you" type hugs. Does that mean he doesn't trip with her....come on now...
For men, I really think it is a control issue. No matter how much you convey to someone your faithfully committed dedication to your relationship, there will be people in your life who may be men that you love. And this means a certain level of attention, concern, and affection that your man may believe belongs solely to him. Most men actually should only be involved with ex-nuns, virgins, and the like, because they think that the relationship is built upon physical expressions of desire. This leaves a small percentage of actions for a woman to display her love towards a man, that no man has ever received from that woman...thus, creating the need for him to get upset every time you give a hug to "Lil James", the cat you slap back in the second grade for grabbing your ponytails the wrong way. I really feel for grown ass women, because I know dudes don't understand what they have at home. But hey...maybe if he don't know what he got, he don't deserve to have it...
...as always, just my fifteen pennies....