OOM,
Actually, it would make sense, but it’s just not true.
One could posit that everyone has a preordained zivug which could be lost through poor choices, and obviously the potential spouse will lose out.
The gemara in Sotah,however, which says that there is a bas kol, does not say that it applies to everyone. Tosafos clearly in dicates that it does not apply to everyone, and as you point out, logic dictates that it doesn’t apply to everyone. Does a baby born with severe mental disabilities, l”a, have a preordained zivug?
So certainly there is a concept of a preordained zivug, but it doesn’t have to apply to everyone, and even for those who have one, it may not actualize.