Romantic satisfaction in an unmodded game decays over time for all sims in romantic relationships, including sims entirely outside of your household that none of your sims are seeing. So, EA-created couples like the Goths or Landgraabs, or player-created couples that you're not playing have romantic satisfaction that decays over time.
If these sims do not load into the world and have enough romantic interactions, their romantic satisfaction will zero out over time and when you go to play the household they will automatically be in a troubled relationship and might autonomously divorce.
This is a problem for anyone who plays rotationally and owns the Lovestruck pack.
