You know how sometimes you meet someone and feel as though you're already familiar with them? You feel a kinship to them, even though you've spent very little time together. The chinese people call this 缘份.
My new theory is that this happens because the new person reminds you of an old friend, and you project all your understanding and affection for your friend onto the stranger. You may not realize the connection consciously, so your immediate affinity mystifies you.
Unfortunately, if the other person didn't have a friend in the past who is similar to you, then there can result in an imbalance. They might find it TMI that you are confiding in them.
Maybe all this soulmate business of people immediately recognizing their "other half" is actually because the soulmates reminds them of someone else they already know well.