In a nutshell, what happens is that the woman in the relationship attempts repeatedly to communicate her needs and her man repeatedly fails to take her seriously enough. She eventually gives up, stops saying anything, begins shutting down emotionally, and sooner or later, exits the relationship. He is stunned and devastated and finally realizes how unhappy she was and wants so much to fix it, to prove his love, to have her back. He tries to convince her that he is, or will be, different. She doesn't want to hear it and tells him she's done and isn't about to put herself through more disappointment. She moves on with her life and does not return to the relationship.
This scenario unfolds much more slowly most times. She starts by asking nicely. She attempts to bring an important concern to his attention. She tries to explain why a certain request matters so much to her. He may respond defensively because he feels he's already pulling his weight in the relationship, working hard to earn money to support her and their kids, helping out, and doing nice things for her. When she says, "I know, and I appreciate those things, but..." he accuses her of criticizing and "always" fussing and nagging.
Or, he might listen and appear concerned, but secretly be thinking he just doesn't get why certain things matter so much to her. Rather than trying to understand from her perspective, or at least accepting what she says as valid and real for her, he shrugs it off and decides it can't really be that big a deal. He might humor her by making a half-hearted effort or do just enough so she'll stop being upset with him and then go back to business as usual.
She feels frustrated and disappointed and the pattern begins. Later on, she'll likely bring the same thing (or things) up again. She may be a little more demanding the next time. If he still isn't responsive to her requests, she may start to complain, bring concerns up less nicely, and repeat her wishes more often and more forcefully. She might "get dramatic" and cry and accuse him of not caring how she feels. She'll say he doesn't listen, and that he doesn't want them to be happy as a couple.
He thinks, "This again? Really?" He again reminds her of all he does "right" and asks why she can't ever give him credit for that. He wonders why women have to bitch all the time and why they're so high maintenance. He thinks he's a pretty good guy. He doesn't run around on her or gamble away all their money. He doesn't even get too mad when she turns him down for sex! Why is she always trying to change him?Does she really think he's going to fall for the water works and hysterics? He's happy with how things are. Why can't she be? "You knew I was like this when we got together." "This is just how I am." Or, he may genuinely feel remorse and say he'll change and he will, for a little while. He likes seeing her happy, after all, but sooner or later, he slips back into his usual routine.