During a camp scene both Gale and Karlach (and Shadowheart) offered to spend the evening with me.
I spoke with Gale first (at random) and his spend the evening was just “show some magic” which I didn’t realize was code. Karlach made no mention of Gale but did a fist pump when I agreed. When I finally spoke with Shadowheart she mentioned that I already had plans (unless?).
Then the Gale romance scene happened and Karlach never brought it up again. Nearly everyone else in the camp gave me a romance option and Karlach and I had a nice moment after fixing her heart the second time, but I think it’s just broken.
Additionally Shadowheart has always had the romance option since it first appeared. I skipped it since we’re just homies, but I think Karlach is locked out for me.