Which townies from any world do you always end up meddling to make them end up together? For me it's these two firefighters from Twinbrook

Is that Cho Sonwhun, one of the homeless NPC pool? If so, she won't be a fire fighter in everyone's game. I think in most of mine she ends up working a register somewhere (since I add in more registers needing staffed).

As for Blaise, she's one of the few that I don't just have NRaas take the wheel on who they end up with. I always shift her to a romance with Alma. Their identical beds are pushed together to mimic a double bed, their house description hints that they could be a couple, and passing off your girlfriend as just your "roommate and best friend forever" is still a thing in small towns. Of course an unmodded game only very rarely shift someone to be interested in the same sex without playerinput and even then it tends to skip creating relationships for people marked BFFs.

Over in Sunset Valley, I sometimes go with the Mortimer-Bella ship but only because I've edited 'grumpy' off of the trait lists for all three of the Goths. Gunther and Cornelia's marriage implodes if they both get in a bad mood (and both the original Sims and Sims 2 specifies Mortimer is cheerful).

I ship Sinbad Rotter with Lucy Ferne! Because of the thematic fit.