There are people in our lives we have such a deep connection with that we're unable to explain the feeling. And that's fine, as not everything in life is meant for the analytical mind. The term "soul mate" has become mainstream lately and obviously it's marketed accordingly. I do believe though that we have several soul mates (for a lack of a better word) in our lives and they don't necessarily have to be our partners.
That you have said very right that it has become very mainstream and it's marketed accordingly. Yes, there are so many people in our lives with who we connect very deeply and we do not always need to analyze our depth of relationships in some brackets. But, I like to dwell upon these esoteric topics once in a while and connect it with something higher then what I can see and hear.