One thing is for certain is that there is much more going on here then her just "turning it off".
So many things are possible in this scenario, I couldn't even hazard a guess, Animalguy.
It used to perplex me why, it seemed, the majority of women would go from relationship to relationship sometimes in very short time (month, weeks, or even days) while men, on the other hand, will suffer terrible anguish for months on end before they let it go. If you don't believe me, well... just read this forum!
First, let me say that I think women are adorable people and this might seem derogatory to some extent but what I'm saying is that the following may be true much of the time but definitely not all of the time. All people are different but sometimes there's some commonality. Had to get my disclaimer in there because heck... there's women on this board!
I truly believe that women are much more sensitive and in tune of a man's feelings than a man is of a woman's feelings. Probably largely in part that women are for many reasons much more able to express emotions openly and without judgment than a man is. When I say " many reasons" I mean upbringing, societal pressure, etc. Since they are able to indulge in the expression and cultivation of their emotions, the emotional nature becomes a larger part of their human language (verbal, physical, etc.)
Men, however, are under pressure to AVOID getting emotional - to keep hold of themselves and behave in a way that befits a man. That's right! Get a hold of yourself, man! Sometimes though, not only do I believe this can be a good thing, but I think sometimes the suppression and control of emotions is absolutely necessary to the man's health and the health of everyone around him.
I'm trying very hard not to write a textbook here, so let's just say that men, whatever the reason may be, will often behave in ways that are deeply hurtful to a women's feelings. Maybe even sometimes physical but let's stick to a normal scenario. Women accept these hurtful things and allow them to build up - sometime even for years. Women often go to almost ridiculous lengths to try to express to a man how hurt they are and oftentimes can't even articulate the reason why so the cry for help will just fall on deaf ears to the man because he says, "She's on the rag. She's crying again and can't even tell me why." And why? Because they are not upset about one single item but a many! It's a year, or two years, or 10 years of pain that are in there. So this is all a double edged sword because while she'll put up with your dumb ass, and the pain of getting cheated on, always late, never call, roll over and go to sleep, it's all getting duly noted inside her. And that big well of shit will eventually start to chip away and the foundation of her feelings for the man.
Time goes by, and these feelings she once felt so strongly for this man are slowly dying, day by day, and the man goes about his business as she doesn't seem to care if he stays out all night, or go out with his friends on her birthday, whatever. He's thinking, "I can't believe she's letting me do this!" Further and further away she drifts until at some point in time the feelings she once had for the man are completely and utterly gone. Then SHE begins to go out, stay out later and later, txt messaging, staying up all night on the internet. Well, she finally meets a guy who's new, exciting, listens to every word she says (or at least acts like he gives a shit) and then the next thing you know.....? What happens?
"We need to talk..."
WHAM!
She breaks up with the man and what do you know? She's dating new interesting guy a week later! A whore? NO, YOU DUMBASS! She was done with your ass months ago! She was already over you and grieved and cried, and was depressed at your loss and the death a looooong time before she uttered the words, "We need to talk..."
So the way it really is, and the way it often appears, can be very different.
I'm sure this is full of grammatical errors and obviously it doesn't apply to every single case but many times, boys, she's over you long before you ever know about it. If she is a healthy female and you hurt her feelings for long enough, she will leave. I give you my word on that.
So my word of wisdom here guys is simply this: Be a good and faithful man, because if you start screwing around, the only ass that will be getting screwed eventually is your own.