Romantic Relationships decay/become negative fast with no interaction

i think I fixed it. My romance bar between two of my sims went into the red after the household to a new lot and after they developed fears around relationships (fear of being cheated on and fear of being alone). I disabled wants and fears in my game. I didn’t love them to begin with, so they won’t be missed. Then I used a cheat to get the relationship back to 100 and it seems to be just fine now. No more rapid decay.