Soulmates are one of the most misunderstood metaphysical topics. Many people believe they have one soulmate, which is not true. Another myth is that once you meet a soulmate that person will be in your life forever. Yet another falsehood is that all soulmates bring only good things in your life.
Believe it or not, there is a such thing as a ‘dark’ soulmate – one that you create a destructive relationship with. (Even ‘dark’ soulmate relationships can have some good in them since they often inspire growth and change.) This article by Llewellyn provides a good overview of soulmate relationships — including those dark ones.