The only one I'm seeing is the normal Womb of Lust, which says it lowers Willpower by 5 per day.
Just went in and used a few of the tea items to raise my Willpower back to like 80. Ended the day and started the next back at 15. No idea why.
The reason this started happening to me was because I was hovering around 40 corruption. So between the curse -5 and the corruption -40, there's max willpower - 45 per new cycle, and then I started hovering around 10 or 20 willpower at day start once I had 'married' Herman. The ring has an effect that tries to force Aura to have sex with him, which builds and builds the longer you don't, so every cycle that you haven't activated 'masturbation is not enough' meant I was losing 45 + 50 max willpower despite using blessed waters or partaking in lewd actions.
Long story short, don't marry Herman until you're ready to be having sex with him, and try not to tank your max willpower too much through curses, or you'll have to consistently rely on emerald teas to function.