It is a wonder that atheists are sometimes accused of being unromantic because our worldview does not afford us belief in soulmates. Well, it seems to me that the opposite is true--that belief in soulmates definitively strips relationships of their true value and that a sober view of (godless) reality offers a much more satisfying alternative. Let me explain.
As a Christian, I firmly believed that God "had someone out there for me." You know... my rib. And it was waiting for this perfect woman that kept me from ever dating in high school and college. I wanted to focus on becoming the right person rather than finding the right person, and when the time was right, God would make things happen according to his will and I'd live happily ever after.
That was stupid.
First, the time one spends dating in high school and probably much of college is, it seems to me, practice for future, longer-term relationships. It is important time for learning about oneself and learning how to relate to others. Delusions like the one I described above steal that away and leave people awkward and clueless.
Second, and more importantly, it is quite unromantic to believe that the reason you are with someone is because you were destined to be together. One betrothed by God is still betrothed. In such a case, you end up with someone because it was some other being's will and not your own. Or perhaps because of the way the stars were aligned when you were born or whatever.
It is much more rewarding to see love for what it is: a uniquely human experience in which we have the ability to choose someone as a long-term companion. You have many options, yet you pick one out from the rest. Then, knowing that life is finite and love does not extend happily ever after, you are able to appreciate each and every moment. It is the fact that love (and indeed life) is temporal that makes it valuable; the fact that love cannot last forever is exactly what sets the time we have apart and makes it special in the first place.
Thank god for atheism.