Why does this happen?

Is it a case of most women simply being easily bored and not valuing stability?

Is it because stability isn't even needed anymore?

Is it because most men are fundementally poor partners and have unattractive qualities that eventually seep through the cracks?

Is it because women have built not only a high physical standard up in their minds but also expect an almost perfect personality to go along with it?

And is this an evolutionary thing, or a cultural thing, and does it imply monogamy is essentially a forced dynamic that most don't fit into?

Is it because women think conciously they want beta traits so they try and condition their man to be more alpha but become unattracted to them once they've succeeded?

Is this all just nonsense and actually, if "I gO oUtSidE" I'll see that every long term couple who spends lots of time together is just the perfect picture of happiness and that comfort and familiarity actually INCREASE sex drive and attraction among women?

Thoughts?