It affects every marriage at one time or another - jealousy. In fact, in a nationwide survey, marriage counselors said jealousy is a problem for one-third of all couples they counsel.

Whether it's a mild or major case, jealousy can have a big impact on your relationship. You may feel jealousy when you experience the heightened threat from a rival. Most of us become jealous when we see our spouse having a great time with a person of the opposite sex - especially if that person seems a little too friendly. No matter how much your spouse may attempt to reassure you, another person's interest in him or her raises all your red flags.

Jealousy can be either healthy or unhealthy. Healthy jealousy is a means to guard your territory. It comes from a sincere care and commitment to a relationship. Unhealthy jealousy includes lies, threats, self-pity, and feelings of inadequacy, inferiority, and insecurity.

Healthy jealousy guards the heart of a marriage. It guards your marriage because it:

* Shows your commitment to the relationship.

* Protects your marriage by safeguarding the relationship against evil attacks.

* Deepens your openness with each other and makes you accountable through honest communication.

* Helps you confront major threats to your marriage and head them off before they become major problems.

God calls you to respect jealousy that comes from your spouse in the form of warning of danger ahead. If your spouse is a secure person and desires to protect your marriage against cracks, you need to listen. Confront the issue head-on by finding the reason for the jealousy and then making changes to keep you both out of danger. Listen to your spouse. A husband understands how men think, so it would be foolish of his wife not to heed his warning. A wife can sense when other people have misguided motives. Her intuition is often right on target.

Regard healthy jealousy as a God-given gift that will keep you out of danger. Men: Trust your wife's instincts. If she suggests that another woman is behaving inappropriately, your wife is probably right. Most women have radar, an innate alertness to nonverbal communication and an ability to translate body language and tone into emotional facts. Your wife probably is able to see these things clearly, so don't criticize or blame her warnings on insecurity. Women: Trust your husband's instincts. He knows what men want and how they pursue it.

Unhealthy jealousy is altogether different. It stems from comparing yourself to others and feeling inadequate, unimportant, inferior, and pitiful. When a person carries this jealousy to pathological extremes, it will dominate a relationship. Some spouses have experienced a lot of loss in life - whether it's divorce, death, or abandonment in childhood - and they may bring unresolved issues into the relationship in the form of jealousy.

A chronically jealous spouse will try to control a relationship through exaggeration, self-pity, lies, threats, and/or manipulation. When the other partner resists, the jealous person reacts by becoming even more controlling. Then the other partner resists further by confiding in a friend or seeking relief outside the marriage. Sometimes this can become a downward spiral.

Here are just some of the effects of unhealthy jealousy:

* You doubt your spouse's honesty and wrongfully accuse him or her, pushing your spouse away.

* You feel worthless and unimportant.