Something that I've noticed, over and over again, is that many women lose their desire for sex after marriage. They're very sexual while they're dating their future husband but once they're married, the sex gradually or sometimes rapidly declines till it's once a year pity sex on his birthday.

Now I understand that some women lose their libido after having children or once they're post menopausal but I'm talking about cases where the couple is young and child free yet the frequency of sex drops off sharply, right after they get married or within a year or two of marriage.

Is this because the husband was a beta provider and sex was merely a way to lock him down? Now that he's married to them and being a nice guy he's unlikely to leave, they don't have to give him sex anymore? Or is it something else ?