unfortunately jealousy is borne out of feelings of low self estime. If you can overcome this and be more confident, relationship wise, you should feel less threatened, more secure and therefore less jealous.
Trust. You have to learn to trust others. It doesn't mean to say that somebody looks at others they fancy them. If your partner feels trusted he/she'll feel good with you..
There is nothing more unatrractive in someone than jealousy, or signs of jealousy. If trust is an issue in a relationship then i would look at any underlying problems which could be the root of any problems. As gammaray quite rightly says low self esteem is a common reason. People need to look at the good things about themselves and stop comparing themselves to others around them. Hope this helps x
I used to very jealous with my last boyfriend. I think neither of us trusted the other. Now I have met the right person, everything is fine. Though I will admit to the odd relapse!