Sadly, I was this guy not too long ago, and this was going to be my answer to this thread. I was friends with this guy since high school, and I was pretty depressed and lonely for a good bit of it near the end of our friendship. I guess he and I always liked the same kind of girls...

Anyways, I was convinced I wasn't going to meet anyone on my own, so I admittedly waited out one of his relationships that I didn't see lasting and then tried to weasel my way in when they broke up. Didn't work (obviously, and because I'm a fucking idiot).

Then he starts seeing this new girl. She's even better than the last one, but I learned from the last time - not going to do this again. And I didn't, at first. But then he dumped her and went back to the one I talked about above... And I guess I kind of became a shoulder for her to cry on, and I ultimately ended up trying the same shit despite the fact that I should have known better.

Anyways, in trying to be a "friend" to the second girl, I didn't lie to her when she asked me if he left her for the first one. I didn't tell her with any sort of malicious intent, I just didn't lie when she asked. Shit happened and my friend of 8 years just cut me off one night (not so kindly, but less... aggressively than I would have expected). I stayed friends with the second girl for a while, but that eventually dissolved, too.

So, I guess my ex-friend is my ex-friend because I'm the ex-friend. I'm better now than I used to be, and I've definitely learned from it, but it was pretty shitty of me. I guess the saddest part is that I didn't even get anywhere with them, so it really was all for naught.