On the contrary I have seen these type of so called soul mate relationships crush long term friendships. But this is my own personal spiritual lesson from such ideas. As soon as I give love in a singular sense there has always been a contrary set of circumstances that reminded me of love for all. In my own experience i have never met two people together as 'soulmates' that could extend that love to others. They have always needed space and separation. Which means it has always been selfish.
Very interesting concept from you.....Your destiny? Perhaps? It is important to take a step back to explore the nature of the relationships we hold in our life.
Some people never come back. They loose connection with friends and loved ones forever. There spiritual life becomes a very narrow personal life venture.