Sims in TS4 can potentially have a happy romantic relationship with basically any other sim. I wish we had an attraction system but since we don't I basically choose myself for them. Many of my sims have "arranged marriages" meaning I know who I am hooking them up with since they are basically children since I play rotationally and only have my sims interact with sims I myself create.
If I want to get out of that and have sims play the filed, and then become indecisive about with whom should they settle down, I just wait and see which sim calls my active sim more for example.
