When you miss an opportunity to befriend someone because you simply didn't recognize that they were trying to be friendly. You wanted to be friends, but through your own social-retardation you turned them away, only to realize later what you have done, and to damn yourself. This kind of behaviour can leave well meaning but socially retarded people lonely and friendless. They just don't know what they're doing wrong, but everyone else does. In a world were perception is reality, they must adjust how they behave to change how they are seen.
The world of the friend-failed is unfortunate. They have every intention to befriend but they missed social queue. The friend-failed often have to undergo social boot camp, including instructions from their friends and others who are more socially adept at interactions than they are. The friend-failed would do well to heed the advice of their companions and those around them, including their parents, to whom they probably weren't listening, and that's why they're socially retarded in the first place.
"oh gees I totally friend-failed today, I told that person I didn't want to go see a movie for them but I didn't give them an excuse. I just said 'nah i don't want to see it'. They probably think I'm a deuche"
"I just totally friend failed, I haven't attended 10 invitations in a row to party by this girl. She'll never ask me again, I've lost my access to this new social circle entierly."
"Who doesn't wanna party? Why didn't I say yes? I'm a social retard, I just friend-failed."