Charlie mentions this in one of his letters about a book Bill has given to him, called The Fountainhead. It’s sounds kind of mean, or even passive agressive, but I think it’s more than that.
Everyone lives their own independent lives. They make their own choices, live in their own paces, have their own friends, etc. etc. Everyone has the choice to share it with other people. When you live for someone, you nearly dedicate your whole life to them, which is a pretty big commitment. Which is why you have to be careful who you share your life with, and set your guard up when necessary.