I believe it's time I add my perspective, now that you lot have given me yours!
I believe in the concept of soul mates, but I don't believe in the concept of "one true loves." I believe that there are people, a hand full of people out there, that you will get along with on every level. You can be identical, or polar opposites, and from opposite walks of life, and everything will mesh perfectly, like two pieces of a missing puzzle coming together. You won't necessarily be romantic together, but you will be the best of friends. These people, if you find them, will be the people you keep in your life for the rest of your life. And if you do become romantic with them...
Well, you've found your one true love.
Does that make sense?