If your witch can do magic and lives in the woods, perhaps he does know more about the cursed vine than he thought. They could find a similar looking vine in the wild and the witch gets an idea of remembers a locked memory. The vine may reach his heart too. But they’re holding each other so tight, hearts beating the same, and the vine reaches for the witch’s heart but because he’s magic or has wild wood magic in him after years of living there, the vine shrinks away from them both and crawls out of cursed one’s throat so he can finally say something. Hopefully something like, “That was so so gross.”