Closest I ever came to playing matchmaker was when I was 19, a friend of mine got hit on by a girl because he drove a nice car (A Mitsubishi 3000GT), and being the inexperienced lunkhead I was, egged him on. He got those digits. A week later it was his birthday, and I used a fake ID to get a hotel room to have the party in (had to be 21 at the time.. also used that same fake ID to get booze for the party). So after about an hour and a half of birthday party, all of us "guests" just kind of look at each other, nod, and by unspoken agreement get up and leave the two of them in the hotel room. It took him a minute to figure out. "Hey, where are you guys going? Is it over already? Wha..." click goes the door, buddy loses virginity.
Yeah, within a week after that she turns into a complete psycho hosebeast and there's a huge messy breakup that I have to go and be the "backup" (I was, at the time, the physically most imposing of our clique) when he goes to her apartment to end it. He's afraid to go inside by himself. She was that scary.
I learned two important lessons from that experience.
1) Do not stick your dick in crazy.
2) Do not meddle in the romantic affairs of others.
I felt guilty for quite a while after that. Still do, a little. If I hadn't kept pushing him to call her, ask her out, take her here, do this, do that, and PROVIDED HIM A HOTEL ROOM, he probably would have been spared a traumatic experience. Ah well. Life lessons learned, character built, etc.