Othello syndrome, named for the Shakespeare character who murdered his faithful wife in an unwarranted fit of jealous rage, is the delusional and erroneous belief that one’s partner is having sex with somebody else. Surprise: Othello syndrome can develop as a side effect of the Parkinson’s disease drug pramipexole, recent research revealed…or it may be a sign of an underlying neurological disorder or brain damage. So if someone you love has suddenly developed an over-the-top case of jealousy, a medical workup is warranted.

In most cases, though, the green-eyed monster stems from a sense of insecurity, not from some underlying medical cause, said Judy Kuriansky, PhD, a clinical psychologist and sex therapist and author of The Complete Idiot’s Guide to a Healthy Relationship. Still, that doesn’t make it easy to handle. “In extreme cases, jealousy can cross the line from insecurity to extreme emotional ‘fits’ that can drive a partner to become physically abusive,” Dr. Kuriansky warned. “If you fear that that line will soon be crossed, get help or get out. The relationship is not worth risking your safety.”

Fortunately, the majority of jealous people don’t turn violent. Yet, for the sake of the relationship and for the emotional well-being of both partners, it’s vital that couples face jealousy head-on and deal with the problem constructively. So here are Dr. Kuriansky’s tips for handling a jealous mate…

In the heat of the moment, offer reassurance, not ridicule. A common knee-jerk reaction to a jealous partner’s accusations is to get angry and scoff, “Don’t be absurd!” That reaction, though understandable, can come across as a dismissal of your partner’s concerns—which will lead to defensiveness and increase the feelings of insecurity that are at the root of his or her jealousy. Better: When your partner’s suspicions are running hot, your most effective on-the-spot approach is to stay calm and be as reassuring as you can. Start with a positive statement about your commitment, Dr. Kuriansky suggested, since that is what the jealous person is most focused on. For instance, you might say, “I love you, and I am completely committed to our relationship. I am not attracted to or involved with anyone else.”

Once the situation has cooled off, do a reality check. Ask your partner to describe the specific incidents that he or she considers to be evidence of suspicious behavior. Then consider this evidence calmly, without getting defensive. Perhaps you do tend to ogle attractive passersby…perhaps you did ignore your partner at a recent party in favor of talking with some fascinating guest…perhaps you have been subtly talking down your partner’s looks, likes or accomplishments. Such behaviors, while certainly not “cheating,” do feed your partner’s insecurities and suspicions. Ask yourself why you behave this way. Are you boosting your own confidence at your partner’s expense? If so, explore more appropriate ways to increase your self-esteem. Or, are you harboring unspoken resentments against your partner? If so, work together to find constructive ways to resolve the underlying sources of your dissatisfaction.

Be trustworthy. Prove to your partner that you are reliable by showing up when you say you will…keeping your promises…and being honest about where you are going and whom you are seeing.

Explore the roots of the jealousy. Knowing what’s behind your partner’s jealousy helps you figure out how best to deal with it. For instance, did your partner grow up in a household where the parents often compared him or her unfavorably with a more athletic or more attractive sibling? Reassure your partner that there is no need to live with those ghosts of the past and that your love is unwavering.

Help your partner focus on identifying and achieving personal goals. A boost in self-esteem can go a long way toward alleviating the insecurity behind jealousy—and that boost comes from personal achievement. Discuss whether your partner tends to be jealous of certain types of people, such as those whose conversation easily captivates others. If so, encourage your partner to develop that much admired skill—for instance, by taking a class in public speaking or joining Toastmasters.

Demonstrate your affection. Everyone likes to know that he or she is attractive, so if you’ve fallen out of the habit of embracing your partner when you say hello, holding hands in public or initiating sex, it’s time to get back in the habit. Reassure your partner that you still find him or her sexy (even if he is losing his hair or she is gaining weight). For a very powerful technique that can help a couple start clicking again, try this suggestion from Dr. Kuriansky: “Ask your jealous partner specifically what he or she imagines is going on between you and a lover—because that is probably one of his or her own fantasies—and then act out that fantasy together.” The surprising thing is, that kind of jealousy-inspiring fantasy doesn’t always involve sex. It could be just having one of those romantic dinners together at a corner table in a cozy restaurant…going to those art openings you used to attend regularly together…or giving and receiving little gifts just because.

Know when to get help. What if your jealous partner is becoming overly controlling (trying to check your text messages, listen in on your phone calls or dissuade you from seeing friends) or seems headed toward abuse (verbal or physical)? Insist that you go together for couples’ counseling. Referrals: The American Association for Marriage and Family Therapy (www.aamft.org)…the American Psychological Association (www.apa.org)…the Association for Behavioral and Cognitive Therapies (http://www.abct.org). A well-trained and objective third party can help you two get the jealousy problem under control so you can relate to each other in healthier, happier ways.