Question: We were given an opportunity to be in a good group of ten. During the three days of the convention, we understood how strongly we love each other. Why do we cry when we confess our love toward each other?
Answer: This is a very good feeling. There are a number of articles on this subject in the wisdom of Kabbalah that explain when and why tears of happiness or sadness for friends, for emotions, and everything else are created. A person cannot contain an excess of emotion within himself, and this becomes tears.
In Section 13 of The Study of the Ten Sefirot, it is explained where tears come from, in what manner they are created. Tears represent an excess of Light that comes into a Kli that cannot hold it, and the Light apparently overflows beyond the limits of the Kli.
From the Convention In St. Petersburg “Day Three” 9/21/14, Lesson 6