I have to agree with @Mikezumi I see the wishes as more game hints. I'm afraid my poor sims must do as they are told especially in the romance department. I would be most peeved if a sim decided to waltz off with someone new when I had gone to all the trouble of creating a mate for them. I tend to keep an eye on the moodlets as well. Despite my dictatorial attitude to their love lives I still like them to have happy and contented lives. Occasionally, in a new game, before my sim has a partner, if they met someone they are attracted to then I let the game progress without my interference. Providing, of course, the sim in question doesn't come with baggage. Sadly so many townies do, being commitment phobes, disliking children etc.
Has anyone else noticed how the game tries to break up couples ? I have a respectably married female sim, with child, in Sunlit Tides and Daniel Pleasant is positively stalking her. Almost every day he rings up asking her to go out on a date and the other night I caught him looking in the restaurant window while my sim and her hubby were inside having dinner.