We need each other in order to overcome our ego and be truly able to bestow to the Creator. This is what He expects us to do. However, you will be able to delight the Creator only when you unite with the friends.
You will not succeed if alone because when you do it alone, it isn’t true bestowal. It won’t work. When you are alone, it doesn’t mean that you bestow; you deceive yourself.
The entire system is designed so that there is a certain filter on your path, and it doesn’t allow you to arrive at that sort of bestowal since it isn’t authentic.
From the Daily Kabbalah Lesson 11/26/10, Baal HaSulam, Letter 52, 1928