This can be so true. I have never believed in the romantic notion of one "soulmate" lover in a life. There is a Buddhist belief that we travel within circles of souls who challenge us in the ways we need to grow. That is actually a perfect fit! :-D If we actually survive and grow through the injury and cataclysms (relationship or otherwise) in our lives, we are often changed for the better.
There are also those beloved soul friends who both challenge and nurture, who lovingly witness and reflect back what you need to realize in order to heal and blossom. In the best Anam Cara (soul friend) relationships, this is a mutuality of revelation and work. And it isn't ever easy.
Do you know the book, "Anam Cara," by John O'Donohue? I think you would enjoy it, Nanette.