Women hate being taken for granted.
I know as a married woman I often feel taken for granted. It often pisses me off.
Women have a tendency to put forth an extra effort for as long as they feel appreciated. Men put forth extra effort only as long as they feel they absolutely have to. Unfortunately for men, showing appreciation is usually categorized as extra effort. Once a relationship is established and the woman is considered "his", then he usually feels like no further effort is needed, and proceeds to slack off. Tsk.
Once they woman stops feeling appreciated, she will stop putting forth the extra effort. By this time, the men have come to just assume that extra effort will always be there and get upset when it's not. But they rarely understand why it stopped in the first place. From there it usually just spirals downward until they go their separate ways.
Hell hath no fury like that of a woman scorned.
