Wait, so you've oogled after the square peg for a portion of your adolescent life and squeezed the edges into the same shape you are, but are now complaining now the square peg has returned to its shape?? You knew the potential problems with distance and her persona and still pursued the relationship.
After such a time together, you either have a decent clue of her character or you're simply outgrowing her as you grow up, but are trying to relive your beginnings. Each year you are together, your tastes actually change. Some people grow together, some grow apart. Both are natural processes.
It sounds like she's testing the boundaries of her angst, with you and, perhaps, YOU are growing out of whatever brought you together, in the first place. What you 'hold on to' are the physicals of her being, whilst emotionally you are miles apart.
You already know the right thing to do, but even if you stay together now you will see the problem exacerbate in the future, leaving you with the problem you have now.
And possibly resentment.
It's a tough one for you, at your age, cos it requires a grown up and logical decision. There are not always the same.
However, it's better to control your own destiny, regrets or not, than have it forced upon you.
