There are soul mates but they are hand-made, not “found”, and the transformation involves both husband and wife. Plus it is not a quick process. It takes 20+ years to complete the making of a soul mate. I can honestly say my parents are soul mates (married 66 years) and my husband and I are also (married 30 years).
I am not sure what soul mate encompasses but I believe that you have made an excellent point about a long term marriage involves transformation of both husband and wife and is not a quick process. The journey has many twists and turns, ups and downs, and is worth the effort whatever term is applied to the love of the spouses for each other. Overall, I would say to everybody in a relationship, just be fair with one another. The road gets rocky fast when distrust sets in.