Like @telemwill WonderfulWhims played a role in my game, but not as much as before sexual orientation was added. That's the main reason I used WW, to make sexual orientation fixed so that my sims stayed true to the orientation I had in mind. I take each sim individually and decide how I want to handle their love life. Some of the premades I will pick their partners. I used to do the same for my sims, but now I let them choose. If I see a sim I think is a good match I may steer my sim to spend more time around that particular sim and see if they will hook up on their own.
When we had whims I would watch and see if they got a whim to flirt with that sim. If they did, I'd clear it, and wait to see if it popped up again the next time they met. If it did, I'd watch to see if either one would start the flirting. If after a couple of meetings they didn't flirt on their own I'd queue my sim to flirt one time and then let them take it from there.