Certainly don't believe in 'the one'. *supresses urge to rant*
But, for someone I love, I would do anything.
But that someone I love would never put me in a position where I would have to.
It's all about compromise: for the last 4 months i've utterly compromised my degree to ensure a relationship which began on decidedly worrying ground was stable, and that we were able to bond. Now it's time to get my head down because I'm failing my degree because of it. So we're spending time apart. I'm going to be in Russia next year: I don't expect him to follow me for the sake of one year apart, and totally sacrifice his degree for short term 'warmth'.
In short: I think that with the one you love and are most compatible with, you both make a series of smaller choices as you go through life, bringing you and your individual ambitions into more of a harmonious balance, with the occasional big sacrifice for one of you: for which the other would naturally feel guilty.