It's only me perhaps , but I love the pack to bits and have not yet seen ant romantic decay on its own (okay if not playing some sims in simyears, but that decay has always been there).
First of all your couples only get that romantic satisfaction meter when you play them. So not all in my save even have it yet.
But however I did test and played a week with other couple, returned to my sweethearts with full romantic satisfaction, it was unchanged. I saw them every now and then at communitylots, but they were all loving to eachother , so I saw no reason why it would even go down.
So, my answer is no, I have not found out playing rotationally having effect on my already married and in love couples.
My rotations are pretty loose and fast tho. from day to max 5 days.