Practically everyone who's been in a serious romantic relationship with all of the deliciously intense and passionate feelings that go with it, have at one time or another experienced jealousy, which is really the fear that -- to some degree -- your partner is not being exclusive to you either physically or emotionally. But it's what you do with your feelings of jealousy that can bring you closer together or ultimately tear your relationship apart.
Jealousy arising from the thought of your loved one with someone else can trigger many feelings. You may believe your jealousy is an indicator that you care about your partner. In this case, you see it as a sign of strength in your relationship; and perhaps it even elicits romantic feelings. On the other hand, jealousy can trigger feelings of sadness, anxiety, anger or even intense rage. That rage could be directed toward a person perceived as the 'object of your partner's affections,' your partner or yourself (in the form of putting yourself down because of your perception of not "measuring up" to that 'other person'). In addition, jealousy can naturally lead to mistrust, which can wreak havoc in every aspect of your relationship.
One of the biggest problems with your feelings of jealousy is that they can become a self-fulfilling prophecy. In fact, there's no guarantee that a relationship will stay intact forever, or that your partner might not fall for someone else; but jealousy can be the catalyst in a chain of events that makes one of these possibilities become a reality.
Handling jealousy requires a look at how much you trust your partner. The fact is that it's normal for him or her to find others attractive from time to time, just as you do, while understanding that this is not really a threat to the relationship unless acted upon. In other words, mental exclusivity is a very high, perhaps impossible standard. Obsessing about this only leads to needless pain.
Overcoming your jealously also requires you to look inside yourself. If you're constantly worried by the idea of being compared to others your partner may find attractive, chances are your self-esteem could use a boost. Ask yourself where is the evidence that I am not good enough to withstand the comparison? Is this completely true? One resource for helping you to overcome these types of negative attitudes and beliefs about yourself is my book Stage Climbing: The Shortest Path to Your Highest Potential.
Of course, there are some situations where jealousy is a sign that there is a realistic threat of your partner being involved with others, despite denials. In this case, jealousy is more or less a wakeup call and a signal to you either to have a talk with your partner or seek professional help to overcome what may be a much bigger issue in your relationship.
Only you can decide if your jealous is insecurity, or an indication that something in your relationship needs a closer look. Before jealousy makes your biggest relationship fears a reality, you have the power to make a change, either within yourself or with your partner, to get your relationship back on the right track. And remember, most people have experienced jealousy at one time or another. It's what you do with it that dictates the outcome!