Answer: They are all the obstacles that are revealed in us, all the rejections, estrangements, and unwillingness to get closer to each other that we overcome and ask for the opposite, to be united.
Any connection between us above any rejections is yet another brick that you add to the Temple, the place where the Creator will be revealed. Just count how many bricks you can lay in one hour, and you will see that you can add more every minute. Even faster.
From the World Kabbalah Convention in Moldova 9/5/19, Lesson 0