Nature's prime directives:
1. Survive, even in extreme enviroments where possible;
2. Procreate.
Corollary: Nature doesn't care whether you're happy about 1 or 2.
Sometimes the two directives are combined. Take the tragedy of female rape: despite the horror experienced psychologically by the woman as she is taken against her will, nature designed her body to have a positive response. This seemingly paradoxical reaction dates back to a much more primitive time where primate sex was simply taken by a dominant male. The female's resistance or non-responsiveness could have resulted in her death. Her automatic positive physical response ensured her survival and contributed to procreation. I'm not saying this is a good thing, only that this is how it is.
The male response to cuckolding is another paradox. Here we have a man who presumably loves and cherishes his wife and would do anything to defend her; yet, the fantasy of allowing other males have their way with her turns him on. Where does this come from? Is it a survival response congruent with nature's prime directives?
Going back to our early primate theory, dominant males ruled the reproductive roost. They had sex with whatever female they wanted, whenever they wanted. If you were a non-dominant male (a fact painfully reinforced on many occasions over time), you knew that fighting the dominant males over a female was futile. You could be severely injured or killed.
Also, unnecessary male fighting when females were in estrus would have taken valuable time away from copulating, which could have hindered reproduction. To ensure that nothing distracted dominant males from mating when females were in heat, non-dominant males were wired to experience sexual excitement at the prospect of watching their favorite females being taken by the dominant males. Additionally, in some primates, females will take mutilple partners during a mating session when they are in estrus, so perhaps the non-dominant male's sexual excitement response is another way of ensuring reproduction. Despite the non-dominant male's initial negative emotional response at the prospect of having a dominant male take his favorite female, the involuntary positive physical response contributes to survival and procreation.
Another part of the non-dominant male's experience could result from his willingness to provide ongoing care for the female and her offspring. The female needs the support of the non-dominant male to survive; yet, on another level, she may despise him for not being strong enough to protect her from the dominant male's sexual advances. She may show this displeasure by engaging in behavior that humiliates the non-dominant male, including spitting, hitting, or throwing feces at him.
In both cases, the females and non-dominant males act out their roles as designed by nature to survive and procreate.
Here is where the similarity between men and women ends, and the danger begins. Many women will confess to having exciting sexual fantasies of being "taken" by a strong male, but very few would actually seek such a real experience. Conversely, a segment of men seem to want to act out their fantasies of watching their females (wives) being taken by another male. In the fantasy of being taken, the woman retains the sense of control over the situation. In the fantasy of being cuckolded, the man has a sense that he also is controlling the action, even if he is having to "submit" as the event unfolds.
Danger comes from the willingness of some men to act out this fantasy. They may unrealistically expect their wives to have some hidden dominant trait and become disappointed when their wives don't live up to their fantasies; sadly, they may end the marriage looking for a more "dominant" woman, or drain the family finances going to pay-for-play dommes. Better for the man to realize that his fantasies simply trigger a prehistoric involuntary physical response best left to the privacy of his own bathroom.
Even more dangerous (and disconcerting) are men who actually allow themselves to become "enslaved" by a dominant female. Enslavement takes place over time as initial resistance is broken down step by step. Part of the brainwashing process of breaking down male resistance includes physical and psychological torture. Some men believe that overcoming their resistance to enslavement is a good thing and shows mental strength.
Get one thing straight: there is nothing positive about allowing oneself to become enslaved in an abusive relationship. The systematic breaking down of someone's will in order to make them "serve" another human and endure acts of humiliation is the dance of anger, not love. Furthermore, there is a paradox of allowing oneself to become someone's slave: the initial consent may have carried the hidden expectation of more frequent of sexual gratification, but many dominant females will not allow their slaves to have intercourse with them; indeed, part of the mental conditioning of the "slave" includes denying him orgasms for long periods of time. Ritual whippings and other physical torture may also occur.
The best thing a man can do is avoid starting down the road to enslavement by taking a clear look at what's driving his fantasies. By knowing that the mechanism of his response is biological and not the sign of some irresistable depravity that must be acted uponin order to be happy, he can more carefully choose safe situations to have non-vanilla sex with his wife by acting out play fantasies together. "Venus On Top" is a good book that will help couples explore the bounds of their relationship in a safe and sane way together. The key here is knowing when to say when by not forcing the other to do something they don't want to do.
If you are currently a slave in a relationship, recognize that you are actually in an abusive relationship and need help. You have allowed your will and sense of self-preservation to be broken down over a period of time. You have been subjected to techniques similar to brainwashing techniques used on POW's. Seek counseling and get to a safe place as soon as possible.