Fear of comitment, or their standards are too high.

Because they are men.

Keep in mind they have TWO heads instead of one....

People always feel committed to change and anything else but the same partner for a certain length of time. It takes maturity and a stable mind to keep the same partner for a good amount of time. Rationality is a plus, too.

I don't think it's that a man is "never happy," as much as it is that human beings are not naturally monogamous, and desire variety. There is, of course, a difference in many males, between desiring variety, and actually going out and obtaining it. I think most men would admit, as do I, that having a variety of mates (or two mates at the same time) is probably a lot more exciting a prospect, than having the same partner all the time. Certain Mormon sects "specialize" in the practice of polygamy, even though the Church of Jesus Christ of Latter Day Saints officially and publicly discontinued their endorsement of the practice in 1890 (if memory serves), when threatened by the Federal Government. The church-run state of Utah didn't wish to lose any of their federal funding, so the practice was discontinued and the variety stopped for conventional Mormons. The late Paul Newman (1925-2008) probably said it best when he commented about the fact that he had never cheated on his wife, Joanne Woodward: "Why go out to get 'hamburger,' when you have 'steak' at home?" Human beings can still "admire & desire" others as potential sex partners, yet refrain from actually doing anything about those feelings, if they truly love the one they're with.

Probably for the same reason that some women are never happy with their partners and always looking for new lovers

Because we live in a disposable society. Everything from cell phones and computers to love and marriage is disposable. It's part of a culture that thrives off the consumer mentality and the constant marketing efforts of corporations. If EVERYONE stopped spending (except on food, and the bare essentials) and did with what they owned or had for ONE YEAR, it might be a start to reduce this trend. As it stands, constant replacement of things has crossed over into the constant replacement of people.

probably for many of the same reasons many females are

The same way women have to have a million pairs of shoes and 500 thousand hand bags. Women will understand men and we'll never understand women.

Insecure, ignorant, impatient and always looking to avoid the displeasure side of life that actually serves to make you a better person iin the end. Always running away from the kinds of pressures or life lesson that refine you. THey are eternally looking to "feel good." Making them in essence, far more miserable in the end. Everyone realizes eventually, no matter how long it takes, that the things they lost out of selfishness and stupidity were those same things that were worth cultivating and having.

this is called amorous dalliance-the sport of girl chasing,girl hunting~lady killing where male use female as prey and talks of scoring instead adoring. girl-chasing and subsequent courtship reach climax of copulation which ends the sequence.,the male move on and search for new female prey.

Because they're "shallow" and always needing their "egos" boosted!

serial lovers are people who are empty inside and think it is the responsibility of the one they are with to satisfy that void. in reality, happy people have happy relationships and unhappy people have unhappy relationships one wonders why a woman would enter into a relationship with such a man to begin with

because women ask stupid questions

I think it is basically about insecurity. The more partners you can attract, the greater the illusion that you are some kind of stud !

Because of a man’s psyche once he concurs or attains the object of his energies he looses interest and looks for another challenge. This is true in his work as well as his personal life. In the case of relationships with others, especially with partners, men work hard at obtaining their goal. At some point in their life they have a desire to procreate and look for what they believe will be the best female to carry on his line. Once he finds this female he woos her until he accomplishes his goal of procreation. This can be with one female or several. This is one of the primary reasons for multiple partners (polygamy) in times gone by. There were times when just like other animals, man wanted/s to assure his seed will carry on. A good example of this is in the deer rut when a buck deer will gather as many does as he can to carry his seed in his offspring. Because as humans we think differently than animals and develop relationships between males and females we refer to as LOVE. Marriage was instituted to show ownership of a woman by a man to in effect protect his rights to the women he could afford to keep. Laws were made to protect those rights (a portion of the 10 Commandments of the Bible). Remember women were “owned” by the man in early history. These “laws” were put in place supposedly to keep the man’s blood line pure and only his. Marriage today is still based on and a hang-over of those laws of old. Today, men still have the same desires to procreate and still look for several or even many women to accomplish this goal; consciously or unconsciously. It isn’t that a man doesn’t “LOVE” his selected partner and “marries” her he does love her but is always keeping his unconscious eye looking for other females to procreate with. Today it is called “cheating”. The times, birth controls, and other factors have changed the playing field, but the goal is the same in a man’s psyche. We have been conditioned today to have only one partner. Men, “love” our partner of choice because of this conditioning and although some tend to rhomb (cheat) they want to remain with their primary partner. Women on the other hand fear their “mate” will find another female better than themselves to procreate with. This fear is called ‘jealousy” as the woman doesn’t want to loose her protection and provider. This fear can be greatly reduced by reinstituting polygamy. Women out number men by a little over 2 to 1 so women have a lot of competition to keep their man and keep him home. This explanation has been long but I hope it has expressed a good and researched base to your question, “Why some men never seem happy with their partner?

Same reason some women are never happy with their partner...... Once you've conquered something, it's no fun anymore. You lose interest.

Maybe because they haven't found the right partner yet.

Not all men have monogamic aspirations. Women more tend to monogamy. P.S. Hard to claim "never" and "always", based on several attempts.