When he shows up at the table where you and she are having coffee, invite him to sit and join the both of you. After he sits, make the introductions, then ask him how his Herpes is clearing up, fake an emergency phone call, and leave the two of them in even more uncomfortable silence.
He will never ask you to play matchmaker again.
Haham I was half thinking of just making off with his beau, that would learn him!! :OD