Ok, after reading all replies, I think I should step in.
Let's start from the beginning of time. Let's go back to the origins of mankind. Then we used to live just like animals, we were not better than any animals, of course, we were pack animals but we were savage with no rules, virtues and free birds. Then reproduction comes into the picture, but in our case, unlike animals, human offspring don't grow faster. Our offspring need long-term commitment and care. So we needed a commitment from a man and protection offered by him from other human males. If you see the animal kingdom, you can observe a particular behaviour, if a male wants to continue his genome, he will kill all young offspring of a female, then mate with her to start his own progeny. It is observed in lions and some big cats. It can be observed in our close relatives, primates too (well, not in all of them). Since women are not robustly built to tackle another male and protect their own children, women needed a man's protection. But who can offer the protection better than the father of her kids?? So that started the foundation for relationships. And a relationship is a checklist. It is a long-term commitment.
There is a reason men have a high libido than women and why they cheat more. It is because they are not wired to raise kids, they are wired to reproduce. A man can have sex more and more with more women, yet he won't lose anything, he literally got nothing to lose. So their sex drive is high. But when it comes to a woman, she always has to pick from N number of options as she is gonna carry the offspring and care for the child for a long time. So she chooses a man who thinks she is the love of her life and gives her emotional commitment (it happens in the subconscious, so the conscious mind is not aware of it).
But no matter how deep the love he has, sometimes his physiology tells him to leave her as he is not built for relationships. So his checklist needs to be completed. His mind needs to be tricked that he is reproducing. Reproduction is embedded in our subconscious. The subconscious contains habits, so to make it understand, you have to speak in its language. Which is "habit". Sex is a habit for men, so by giving him sex, you are satisfying his habit and keeping his subconscious in check. When the habit is not satisfied, he will always go looking for other women or at least he will find a way to satisfy his habit as it is built in his nature. So better give good sex to your man. The more good the sex is, the less the chance for cheating. And when men grow old, they lose libido so even if a woman can't satisfy him at that age, there is nothing much to lose.