Psyringe: As far as I can tell, this is really the only other game that ever tried a mature/serious approach on a dating sim (or something similar). Googling for games mentioned together with that one might have yielded the answer.
I don't quite know how to Google for something "like" the search terms. =\ Anything like "Games like "Girlfriend Construction Set"" just seems to lead to modern dating sims. If anywhere in the search terms you include "Cathy" you just get flooded with hits from Atlus' new game "Catherine". Especially if you include "Dating Sim" in the search terms.
Smannesman: OK here's the next game.
My guess would be Girlfriend Construction Set, but really it could've been any of a gazillion interactive fiction games. I hope you enjoy your extra inch of e-peen for winning a round.
Definately Dog's Life, but that's already been said now.
EDIT: Apparently when I refreshed the page it didn't alert me to a new page being formed.