do you make a partner for your sim or find NPC?

I have never made a partner for any of my sims. (Unless I made a family Mom/Dad in create a sim). The vast majority have found their partner via NPC or one of the pre-made families. I have also downloaded some sims from the gallery just to add different sims to my game that weren't just generated by the game. I currently have one sim born in the game who has gotten engaged to a sim I got from the gallery. I am sure I will soon have sims that were born in the game getting together.