I'm still figuring out how the romantic satisfaction works. I have noticed that if your sim couples are marked as unplayed they quickly develope fear of being alone and that destroys their relationship quite fast. I have had Fengs and one of my own sims couple divorce because their relationship went so bad. However it doesn't seem to apply on played sims. I have been worried of my favourite couple, but they are doing perfectly fine.
I have used Cupid's Corner app also just for finding friends for my sims, and I like the new dates more than the old ones, because you can pick what your sims are going to do during the date, so the dates feel more versatile.
If you have and like playing Jungle Adventure it is also good to know about this "bug". https://answers.ea.com/t5/Bug-Reports/OPEN-JA-LS-OR-Married-Couples-appearing-in-special-vacation/td-p/13916062/highlight/false