I haven't been through a lot and I also haven't been in this world that long yet.
Still, there are all sorts of people in the world. Sometimes I think about random characteristics that are almost impossible to find in a single person, yet I still imagine a person that might either want or have all those traits. And then I go out, meet new people, and soon find out that the person with all those random characteristics I thought about was real, even if it's just an acquaintance of the person I met.
So it's quite possible to an extent, for someone that's meant to be for certain people (meaning, not all) in the world.
A specific person for every single person in the world, though? I ain't so sure. But who knows? Heck, there just might be someone out there for everyone with all those many influences, qualities, and other factors that make people alike, and it's a pretty good thought to think, even if that person is on the other side of the globe.
Not sure if everyone would be able meet their special somebody out there in their lifetime, though.