It was in the time of the Greeks that Zeus split human's in half as punishment for their pride, separating not only bodies, but splitting souls in two, dooming humans to long and search for the other half of their soul for the entirety of their lives. And from this mythology sprung forth a vast array of tales about "star-crossed lovers" and dozens of similarly structured romance novels.
I may seem cynical, but trust me, I'm one of the biggest saps for passion and romance there is. But I think today's culture has destroyed what "soulmate" means. Just because they know what food to buy you when you're angry at them, doesn't make them your soulmate. That makes them observant.
No, soulmates come in all shapes and forms, and all throughout your life, despite what mythology and popular culture say. They come in the friends who just know when you need someone to reach over and hold your hand. They come in the strangers who pass by and look you in the eyes and smile when you feel like the world is against you. They come in a few kind words that you didn't know you needed to hear until they were said. They come to stay in your life for the rest of your life, or they come for small moments. They sometimes come in the form of a lover. But that's not always the case.
I believe that any soul that reaches out and touches yours, even for a moment, can and should be added to the list. Because for that moment, those months, that year, a lifetime, they knew you at your deepest, your most vulnerable.
I think it is so valuable to think that anyone could be a soulmate for you. This way, you don't have to feel quite so alone.