People make love/have sex for a variety of reasons — fun is only one of the reasons. Another obvious one is to procreate. Remember all those noble women who used to endure their husband's advances while 'thinking of England'? Sad to say, some women still feel that way.
The less obvious reasons for having sex are the subtle ones, the hidden ones that many people are not even aware lie at the base of their desires. Let's take each in turn.
power
By giving your body to, or withdrawing your body from, another person, particularly a partner, you are placed in a position of considerable power. You have something another person wants very badly and so you might be able to use it as a bargaining chip. Wielding this power can be a conscious or subconscious process. Studies show that the three main reasons why people go off sex with a partner are anger, spite and boredom. I think we can all relate to the last one, especially in long-term relationships. The other two are more insidious and need to be watched so that the substance of the relationship is not damaged through sexual power being wielded in this way.
If two people have just had a quarrel, it's quite reasonable for one or both parties to go off sex for a night, or even several nights. However, if only one is angry, and the anger has not been expressed, sex can easily be used as a weapon. Refusing sex then becomes not a matter of fatigue or comfortable abstinence but rather, punishment. This is more strongly evident when resentment builds up over a long period of time, perhaps even years, and is then turned into spite. There does not have to be any real grounding for these feelings, which can stem from a simple misunderstanding or an insecurity on the part of one of the partners.
For instance, if a woman hears a rumour that her husband is having an affair with a girl at work, she may be too scared to ask him straight out, so she just 'stews' about it. Sex is out of the question as she's feeling hurt and vulnerable. The days turn into weeks and he's wondering why he's being continually rejected. He, in turn, starts to get resentful and maybe even suspects her of having an affair! This cycle can continue until serious, possibly irreparable, damage is done to the relationship. The solution, of course, is open, effective communication. Whether you have been deliberately or subconsciously using your body and your sexuality to punish, wield power or score points, think about it and see if you can come up with a more positive way to deal with your anger and problems.
comfort
Just as food can be used for comfort, so too can people have sex to feel better about themselves. Any of us can masturbate, pick up a casual partner, or use our spouses for self-satisfaction rather than for genuine sexual pleasure (although that may be a side-product of the process). It's a false sense of self-esteem that associates sexual desirability with true value. The thinking is, 'If I'm good enough to have sex with, I must be a worthwhile person'.
Sex, like alcohol, food and hard drugs, also acts as an anaesthetic for life's pain and problems. For those moments or hours you're drinking, eating, high or screwing, you're 'safe', you can forget your troubles. But, as I always say to my students and clients, you still have those same issues to deal with when you sober up, come down from your high, stop eating or having sex. These are fleeting cures at best, and at worst, they add to the pain of self-loathing which is at the root of much addictive behaviour.
Sex can be used as a distraction, as an antidote to boredom, to fill in time. For me, that's a waste of a precious resource. I don't say that sex has to be a big deal every time or that the earth has to move for every orgasm, or that every coupling couple have to be madly in love — but sex is a natural pleasure, a biological reflex, if you want to take the emotion out of it. It should not ever be 'endured'. Those who feel that way are cheating themselves out of one of life's greatest gifts.
bargaining
Sex is sometimes used to get things we want. A cynical view is that women give sex to get love — and even marry for this reason. I think it's more complex than that. Both sexes are capable of consciously or subconsciously, using sex to bargain for other desirable commodities. For instance, many women tell me that they sometimes have sex with their husbands in order to soften them up for bad news or to get something they want, such as extra shopping money. This in itself it not particularly harmful as long as it's done in a lighthearted spirit and nine times out of ten, the fellas know it's being done to them!
However, if habitual, this behaviour can lead to the sex act losing its original point. Instead of being a way for two people to bond, it descends to the realm of cheap blackmail and is demeaning to both parties. Eventually, sex cannot be enjoyed unless there's a payoff.
control
Sex is sometimes used to control a partner in a long-term relationship, or get something else in a casual relationship. A woman might keep her husband at home on a Saturday night with the promise of sex, for instance. Or a husband may flirt with all the women at a social function to remind his wife that he's still attractive to other women and that he could play around if he wanted to. Specific sex acts can also be used as bait, such as oral sex being given only when other things are going well in the relationship. In a casual relationship, sex is sometimes offered to get drinks or a meal bought, or to prolong the association.
Disempowered partners in relationships often feel that they're forced to have sex whether they feel like it or not. This can happen with both genders but, more commonly, emotional blackmail is used by males in this context. It can be as overt as 'I keep you, so I can have sex with you anytime I want'. Other times, it may manifest as sulking, bad temper or even violence if sex is withheld for any reason, even a good one.
self-esteem/ love
Some sex addicts associate sex with love, so for them, having sex automatically means being loved. Of course, the two things can be totally separate.
Women with low self-esteem, in particular, will usually go to bed with a guy they've just met because they don't think they can hold onto him any other way. In other words, they value themselves so little that they habitually give themselves away to strangers.
This becomes a very destructive pattern that erodes self-esteem rather than enhances it. Each time a relationship fails to become more than a one-night stand, self-hatred grows.
Men get their false self-esteem from the sex act itself. Our society places a lot of emphasis on male sexual performance, and therefore, a man who is 'well-hung' or who can sustain an erection for hours feels important and desirable.
People who fall into these sex traps are forgetting that true self-esteem comes from within us, not from any single act of achievement or the approval of others.