Happens a lot around girls, who in certain cases can have numerous unconsummated relationship wishes, making life extremely hard for friends who keep losing track of who's out of bounds and who is not.
Situation to illustrate: Rachel totally forgot about the unconsummated relationship wish of her friend Angela and went on a date with Brad. Angela is now angry with Rachel and won't talk to her, even though she had a date with Kevin and has no business with Brad anyway.
Is also very common regarding ex-boyfriends.
Nick asked me out last night, isn't that cool!? - Yeah, kinda... you know, I really don't want you to go out with him. - Why? Is he a unconsummated relationship wish of yours?'