I don’t know, I think it depends on if you include the origin of soulmates in the definition you use. If you define soulmates as people that were made for each other, then yeah I suppose that creation is out of their hands while defining who they are (and maybe implying that something/someone did the creating). When I think of soulmates I tend to think of persons that are perfectly suited to be together without necessarily needing a cause for it.

It would seem unlikely that every person has a soulmate or that every set of soulmates would meet each other, but it seems possible for such people to become perfect for each other through free will.

Also as a tangent, I misspelled it as ‘soupmate’ in the dictionary at first, and if I had a soulmate we would probably be soupmates too :P

Or... maybe predestination is true in the sense that the universe is just physics and therefore theoretically calculable. I suppose that's less romantic though.