I knew a couple of women like that. They had beautiful families and husbands who adored them. And then decided something was missing, they wanted more. Selfish is the only way to describe them.
That was pretty much exactly the backstory of the '70s sitcom One Day at a Time. Married woman (played by Bonnie Franklin) decides one day that marriage isn't for her. No reason given, no explanation, she had "just chosen to be single."
This caused some tension between she and her ex-husband (played occasionally by Joseph Campanella); the angst was blamed on him as being a neanderthal male bumpkin who wasn't in tune with the times.
As far as feeling entitled to any kind of explanation, he was welcome to just go pound sand. The fact that he had any expectations whatsoever of such a thing was evidence of his atavistic phallocentric participation in the dominant male patriarchy, and therefore completely without merit.