And when I say drain back I mean really really fast. I would queue up interactions to increase their romance and they'd have just go the woohoo interaction back but before I could use it they had already lost all the romance they had gained back.
Having this issue as well. I only noticed it this last week or so playing. My sims have a close relationship, their married, soulmates and have a steamy relationship as well and I can use mccc to cheat their relationship in in less than on sim work day they are at -292 from 100 at the beginning of the day. At this point I am close to disabling lovestruck if that is the issue. One of my households this was happening to, yes their had a strained and difficult relationship and in one sitting of putting a puzzle together they started yelling at each other then the wife divorced him. All in the span of 3 sim hours or so. And yes I can keep using mccc to cheat the relationship but the negative moodlets and their actions make it a minute point.
I am having the same issue on my game. Was happening a few months ago but it seemed to resolve itself and now all my sims in relationships are about to divorce because of this bug.
