[ARCHIVED] Romantic Relationships decay/become negative fast with no interaction

I had the same issue and did the date thingand they were both so happy and I got the pop up that said they will now just increase their relationship without much doing. It still kept happening that the romance bar dropped to zero and then I got it! 

He was turned off by fitness or pessimistic Sims. So every time she was sad and/or doing yoga, he startet to hate her RAPIDLY! Only took like a Sim hour to get that bar to zero.

I don't know if it's a bug, but turn offs are extremely overpowered.I like the idea that they are not100% for each other but make it work. Not like this. They are married and have four children together. Her doing Yoga is not the hill to die on, dude. 

EDIT: this worked only for a moment. Now it's decaying rapidly again...