I flip back on forth on believing in the concept of soulmates but that might be because a few years ago I once thought I had met my soulmate on SS as well and we really clicked in a lot of ways but ultimately she felt otherwise so I guess it wasn't meant to be.
I think the reality is that for every individual there are actually dozens or even hundreds of individuals in the world that could make a worthy romantic partner for them but it's all up to fate, or I guess this supposed red thread, to literally weave itself around and create these connections through getting to know each other and shared experiences.
Edit: Each of those folklore tales about the red thread describe times when most people were confined to their villages or small towns so of course it was much easier for people to find their soulmates because they had no other choice. Imagine if those guys had had dating apps or even had to contend with the One-Child policy creating a saturated male-to-female ratio.