when a woman checks out, she's gone. That's what I learned. At most, she'll be cool for a few weeks before she does the distant thing again. When you leave, of course they throw a tantrum. It's sort of like kids who have a bunch of toys they never play with. When their parents say they will give the toy to another kid, they throw a tantrum, play with the toy a little while, and then go back to their new toys. Same thing with women. They get bored with you, they have a new toy they are with. You threaten to take their old toy away (you), they are attentive for a little while and then they go right back to being busy and distant, as they are playing with their new toy.
All you can really do in this day and age is accept the transient nature of most relationships. Enjoy the person while they are here, but don't be too caught up on them, so you won't be emotionally distraught when they leave. "You're here with me? Coo. Oh you want to leave? I wish you well."