Key words are "overly jealous". By that I mean there is a degree of jealousy which is a natural emotion. Jealousy beyond that is cause for alarm. Also, extreme jealousy is a normal reaction in the case of real reasons. The most notable example of normal jealousy occurs in the following scripture:
Numbers 5:12 “Speak to the Israelites and say to them: ‘If a man’s wife goes astray and is unfaithful to him 13 so that another man has sexual relations with her, and this is hidden from her husband and her impurity is undetected (since there is no witness against her and she has not been caught in the act), 14 and if feelings of jealousy come over her husband and he suspects his wife and she is impure—or if he is jealous and suspects her even though she is not impure— 15 then he is to take his wife to the priest.
The previous scripture can also be applied in the same manner for a jealous wife. In short, if a woman gives the husband reason to truly believe she has been unfaithful, the husband is rightfully jealous, and they are to go for spiritual counseling. The husband in this case has a rightful reason for being overly jealous, and jealousy, in this case, is justifiable and a normal emotion. The husband is making an attempt in restoring both the marriage and righteousness.
"Normal jealousy" is when a relationship triangulates. Normally the triangulation is sexual in nature and may be real or perceived. An example of normal jealousy is when a husband or wife loves the spouse so much that even the thought of competition gives way to mild anxiety. For instance, the wife may feel that exclusivity is violated when the husband pays too much attention to the Dallas Cowboy Cheerleaders. That's normal "uptightness" that the husband would even have the least notice of another woman. All women know that their husbands do find other women attractive, but it still intimidates!
Those who are overly jealous can get sick! The psychiatric term for one who gets jealous to this extreme is "morbid jealousy" or "delusional jealousy". It's a disorder where the person has strong delusions that their partner is being unfaithful although there is no evidence to back up the thought. People who are morbidly jealous imagine all types of sexual events are occurring and build a case in their mind with a worst case scenario. An example of this would be when a man smiles at a woman or teases. Before the morbidly jealous person is through the "smile" becomes a "knowing exchange of intimacy" and the "teasing" becomes "mental foreplay". In each case the man is usually being friendly or at most having fun with attention for which all people desire. Rarely does the "friendliness" result in sexual encounters, mainly because people will not ordinarily desire or risk the consequences of triangulation.
Morbidly jealous people have anxiety. They feel betrayed by their loved one because of their own insecurities. The third party may seem more attractive, smarter, more fun or sexier than the one who is insecure. In many cases the third party may truly have those impressive "credentials", but the case is likely, if he or she is that extraordinary, they likely won't be attracted to the spouse or other loved one. All men and women fantasize some. Face it and live with it! That doesn't mean they're going to run away with every blond they see! Is this wrong in God's eyes? Admiring beauty is not; lust is!
Lust is wrong! Although most people do it at some time or the other, that doesn't make it right!
James 1:14 "But every man is tempted, when he is drawn away of his own lust, and enticed 15 Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death."
No excuses here! Lust is wrong yet we all have done it. That's why Paul tells us it's better to get married ;"It's better to marry than to burn"! (1 Corinthians 4:9). That's a big reason that I got married and a big reason many others do as well! The second largest reason is that the emotion of "love" requires exclusivity! Just as God is a "jealous God" and wants his bride (us) to have an exclusive relationship with Him and Him alone, having love for other gods is called syncretism riles God's ire! Likewise, triangulation (the introduction of a third person into a sexual relationship) is called infidelity, and it causes humanity to be jealous of one another! You have lusted and so has that person you love. Wrongful emotions, but human emotions which we all have.
Don't condemn the one you love for having the same weakness we all have. It would be great if we were all beyond sin, but unfortunately, we're not! Trust can go along way and ensuring that triangulation doesn't occur because delusional jealousy will alienate that very one who you're trying to keep! A mate of the morbidly jealous is in a mental jail. For all practical purposes morbid jealousy creates extreme unhappiness on the part of the mate and emotional sickness on the one who's morbidly jealous. The person who is delusional in their jealousy provokes their partner!
Colossians 3:19 (ESV) "Husbands, love your wives, and do not be harsh with them. "
Ephesians 5:25 (ESV) "Husbands, love your wives, as Christ loved the church and gave himself up for her..."
These two verses pretty much mean "don't provoke your spouse" since they apply equally well to husbands and wives. By accusing and blaming, the jealous spouse is "provoking". The wrongly accused person feels resentment and anger, especially when there is absolutely no cause for the mate to be jealous! The mate of the morbidly jealous person has already been arrested, tried and sentenced! Life afterward is unbearable! A man may avert his gaze even while talking to keep the woman from mentally torturing him! The relationship is in jeopardy:
Proverbs 25:24 "It is better to dwell in the corner of the housetop, than with a contentious woman in a whole house."
The man may resort to the a "corner of the housetop". It may be on the basketball court, fishing hole or even work, but the man will find that seclusion to escape contentiousness (quarrelsomeness)! A quarrelsome spouse is one who blames and fails to accept reasonable justification. No matter what the husband says, it's refuted by more blame and yelling! It may appear that only women can be contentious! No, I'm not saying that. The example is for women, but men are equally able to be morbidly jealous and contentious.
Morbid jealousy, as mentioned, can cause sickness. Anxiety impairs both emotional and physical well-being. One may suffer heart burn, feelings of suffocation, distress, depression and even tiredness and insomnia. By being unfairly jealous a person creates a dysfunctional relationship and further alienates the partner. The more sick the jealous person becomes the more estranged is the relationship. Finally, escape must occur for the systems (persons) to seek healthiness. Oftentimes divorce occurs because of delusional jealousy.
What can one do to prevent the sickness of delusional jealousy or even being overly jealous? Trust! A spouse must feel confident that their mate is faithful to the relationship. That trust must be embraced when the spouse is "guilty" only of normal social interactions. Men do have women friends and women do have men friends! Enjoy those friendships yourself and trust will be instilled. A man doesn't desire having to hide a opposite sex friendship and neither does a woman, The concealment of a friendship doesn't mean infidelity, it means fear! Fear of being falsely accused.
Mutual trust tears down that jail! Mutual trust rids oneself of anxiety!
1 John 4:18 (ESV) "There is no fear in love, but perfect love casts out fear. For fear has to do with punishment, and whoever fears has not been perfected in love."
In a circular cause and effect, fearlessness in love enables trust and trust in a marriage removes fear from marriage. On the other hand delusional jealousy in love destroys love.