Are soulmates real or is it just chemicals in the brain?

Now i know nothing of this because i nver been in love before, but some people told me that when they found eachother they just knew , or something like the felt the floor slipping from under them or some crazy bs like that. Or something that when he and she look into eachothers eyes they can tell all there thinking. I cant comprehend that lol, but how is it that a girl and a boy can go threw many relationships meet many people throughout there life, but when they meet eachother they fell this strange feelings that my cousins describe. I dont get it. do we have satalites in our brain or somethin?? I mean what is it that triggers this so called feeling with him or her that doesnt seem to emerge on your past relationships?