Learn to be ok with not being invited, included, or considered.
Anyone who has ever been betrayed by a friend or had someone use them by pretending to be a friend may give voice to this phrase in anger or disgust. When a stranger betrays you it may not bother you, but when a close friend does it the pain can be almost unbearable. This could cause you to become distrustful of others, swearing off friendship because of the previous experience.