It is said that love is the opposite of hate, so those we intensely hate can someday become those we most passionately love. Is this truly the origin of many or even most “soulmate” bondings?

We would disagree with this characterization. What this question is really reflecting is the all too frequent situation that people who have a reason to be attracted to one another have, in addition, much karmic baggage and that baggage gets stirred up from the experience of being in a personal relationship with potential importance and increased intimacy. It can be a trigger for many past karmic hurts, disappointments, and woundings. So, again, the fact that love brings pain along with it is not a characteristic of love per se, and the desire for love and the requirements, somehow mysteriously, for a period of fear and loathing that somehow transforms into forgiveness and then deep love and a passionate intensity. It is simply that people have a capacity for love and passion but, being people, come with various types of liabilities, having been wounded often in many lifetimes, and this creates complexity and vulnerability to having things stirred up that can get in the way of a smooth new relationship forming and being maintained for a prolonged period of time. There may be many points of friction that arise from the stirring up of old karmic wounds on the part of both parties, and this will simply require lots of healing attention to smooth off the rough edges and allow people to get along without conflict and have the relationship survive over the long haul.