Why people enjoy BDSM relationships

Psychologically speaking, there are a vast number of reasons why someone might be into or enjoy BDSM. Someone might be attracted to it for one reason, or many reasons.

A big reason why a lot of people like BDSM is because it's a way to experiment with control. For a submissive, having control over your life or your body taken away can be very exciting. You don't know what's about to be done to you and you don't have any way to stop it (technically a submissive can always use the safe word to end the scene, but the psychological effect is still present regardless). That uncertainty and fear that comes from giving up control is a very powerful feeling. In a way it's similar to the appeal of horror movies. People watch horror movies because, on some level, being scared is fun.

Conversely, a lot of submissives also find that surrendering control to another person is a very "freeing" experience. What I mean is, freedom and responsibility are two sides of the same coin. But while freedom feels good, responsibility is often stressful and taxing. By giving up freedom, a submissive may feel "freed" from responsibility and therefore freed from the stress that comes with it, if only for a moment. So long as they are being controlled, they no longer have to worry about paying the bills or keeping up with the Joneses or whatever. Suddenly that all becomes someone else's concern, and that makes them feel better.

Control can also be a big factor for dominant people, but in the opposite direction. Being given control over another person's life or body can feel very empowering. The knowledge that you now have power over someone else, and they will not only willingly but gladly submit to your will, can be very exciting.

Another common theme in BDSM is trust. In many ways all BDSM is an exercise in supreme trust. The submissive is trusting the dominant to go only so far and no further, and to protect the submissive from undue harm. For a submissive, being able to trust someone so deeply that you are willing to literally put your life in their hands is very romantic. And for a dominant, having someone in your life who is willing to give you that kind of trust can be profoundly moving. Trust and romance have always been deeply intertwined and in that respect BDSM is no different from marriage (insert "ball and chain" joke here).

Fantasy is another big element of BDSM. For instance, one of the most common themes in BDSM is the "Damsel In Distress". A lot of people consider this an exciting fantasy because it includes a lot of appealing factors. There's the actual bondage of course, but there's also the "danger" and the "fear" aspect, which I mentioned earlier. So a couple might act out a DiD scene with the submissive playing the damsel (and no, the damsel doesn't have to be a woman) and the dominant playing either the villain who ties the damsel to the railroad tracks or the hero who rescues the damsel (and then takes her back to his place for hot lovin' action). But more than anything else, the simple act of playing out a fantasy is very appealing. By acting out a fantasy you get to be someone else, and anyone who's ever done any stage acting can tell you how fun that can be. Fantasy and role-play are probably the most common forms of BDSM out there, because it has such an obvious appeal. Even people who are horrified by bondage and S&M can usually see the appeal of role-play in the bedroom. Why else do you think lingerie stores sell sexy costumes?

So that's the bondage and the domination aspects explained as well as I'm able to explain it. The remaining aspect of BDSM, the enjoyment of pain (commonly referred to as S&M), has much the same appeal. It plays into both the control and the fantasy aspects of BDSM. Often a BDSM scene will involve the submissive being "punished" for some reason or other and it may also involve a fantasy to justify it. So for instance, you'll often see fantasies like "teacher and naughty student" where the dominant plays a teacher who has to physically discipline a misbehaving student (the submissive). There are more variations of course, but you get the point.