Women become content and stop giving to the relationship first. Satisfied by what they desired, they sit in the phase rather than making efforts to sustain and progress it. Naturally as the chaser, the man makes the effort to keep pouring into, prolonging an often dying relationship. He attempts to continue to give seeking equal exchange; as long as she's satisfied, she continues on blissfully ignorant.
Many women are selfish and this develops from the survival and princess mentalities taught young. For some it's entitlement from being spoiled, others being told to never rely nor trust men. Many believe in getting their own, being given their own, and giving nothing back.
Again, what is the value of a relationship to a man? With little to no compromise being given, where does value lie outside of sex? With communication barriers and counter hardwiring, expression is difficult to be made and received. Often times biased communication is made, the man makes his efforts to change along with his request of change, to receive portions in exchange that may be shortly granted. An incentive is absent for a man to continue to pour. This soon becomes withdrawal and accepted defeat before officially mentally checking out.
Now when he attempts to leave, again, triggering her survival she'll fight to stay alive, meaning fight to keep him, and if opting to stay, restarts the cycle of contentment rather than attempting to meet previously requested demands and pouring into the relationship.