Well, since everybody's chiming in with their own experiences, I'll retell my tale...
There once was a snowth named Snowth, who knew a girl refered to as She-Who-Shall-Not-Be-Named. They used to be friends, and after over a year of friendship, Snowth suddenly fell madly in love with She-Who-Shall-Not-Be-Named; he didn't understand why, after over a year of friendship, and never having any feelings for her before, why was he suddenly so deeply and hopelessly in love with her? To complicate matters further, Snowth was torn, because he was well aware that during this same period of time, She-Who-Shall-Not-Be-Named was already in a committed relationship with another guy who will be known as The-Jerk-Who-Is-Not-Steve-Martin. Snowth couldn't bring himself to admit his feelings for She-Who-Shall-Not-Be-Named, because he felt it would only complicate things further; while it certainly would have been a weight lifted off his shoulders, he essentially would have just dumped that weight on her shoulders, and she didn't deserve that.
Are you following this?
Snowth thought the best thing to do was try to erase She-Who-Shall-Not-Be-Named from his life, because he felt it wasn't right to be in love with a girl who was already taken, however, friends close to Snowth, including his best friend, who doesn't have a very noticeable Canadian accent, but DOES say "sore-ee" instead of "saw-ree" suggested that he remain friends with her, on the grounds that wouldn't it be better to have that little bit of her in his life as opposed to not having her at all? It wasn't easy, but Snowth remained friends with She-Who-Shall-Not-Be-Named, despite that his feelings for her still weren't going away for quite some time, and at times, he couldn't quite stomach whenever she would start gushing about The-Jerk-Who-Is-Not-Steve-Martin.
Have I lost you yet?
After additional time had past, She-Who-Shall-Not-Be-Named's flakiness became more and more apparent to the Snowth: she would go for extended periods of time without contacting him, sometimes ignoring him altogether, and even pretending that he doesn't exist. But why would she do that? If they were such good friends, why didn't she make any effort to keep in touch with him, or respond to any of the messages he left for her, like sending good wishes on her birthday and crap like that? After Snowth received more words of wisdom from other friends of his, such as the half-bat/half-ghost/half-demon/full-crazy creature he mingles with, Snowth reflected on the events that had plagued his pathetic existence - he took notice of how She-Who-Shall-Not-Be-Named would only speak with him whenever she needed something from him, he also reflected on how he did so much for her without very much appreciation or anything else in return - he finally realized that She-Who-Shall-Not-Be-Named was not such a good friend after all... in fact, she turned out to be a pretty lousy friend.
Why are you still reading this?
Snowth finally saw She-Who-Shall-Not-Be-Named's true colors, and realized that she was simply a selfish giraffe, whose only concerns in life were herself, and things that went on in her own little fantasy world that she lived in that never reflected reality. After realizing all of this, the feelings that Snowth once felt had disappeared. After three years of adoring someone he thought was his friend and he thought was the love of his life, Snowth FINALLY fell out of love with She-Who-Shall-Not-Be-Named, which is something he had been wanting to do since the beginning, back when he felt he wasn't right to be in love with someone who was already taken. To this day, Snowth still hasn't heard anything from She-Who-Shall-Not-Be-Named, and it's has been a roughly a year and a half since they last spoke. He has sent her messages that have gone unanswered, and he sent a Christmas card to her that came back with "Return to sender, no longer at this address" on the envelope. But it does not matter, because now that Snowth has a better understanding of the real person, he could care less about whatever the **** She-Who-Shall-Not-Be-Named is up to, and as far as he is concerned, she doesn't exist to him anymore either.
And so boys and girls, the moral of this story is simple: some friends are not your friends, and those friends suck, so don't ever fall in love with them, because love stinks.