There's no such thing. Or if there is it would be as rare to find such a person as it would for both of you winning the lottery. Couples don't stay together for many years because they love each other a lot - people that love each other get divorced every day. The ones that stay together do it primarily because they're good at tolerating each other.
That said, if you want more of an explanation from her, then ask. She owes you that much. Maybe it was you and maybe it wasn't, but only she can answer that question.
Personally, I've always viewed love affairs like I would any other relationship one might have in life, such as relationships with friends, ie, they come and go. C'est la vie. And by the time a relationship ended, I was usually more than ready to be done with it - in fact often happy to be done with it. I don't want to be with someone because we're good at tolerating each other. That's not happiness to me, that's a prison sentence.
At the very least, a relationship ending isn't worth ruminating, and they're certainly not worth feeling lost. If things don't work out, look at the bright side: you have freedom, and freedom is always something you should feel good about.
[I understand you were looking for a female's perspective but I do have some experience in this particular area so I thought I would chime in.]
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Love Guru