Thanks for the flowers and the confirmation! I wasn't sure about Karlach, but guessed that with Astarion and my Gith necromancer Tav, Sava, it was just due to low approval. Thayvian necromantic tomes should only be handled by trained professionals! Mutual antipathy until late in Act 3. A lot of people who didn't play the game thought it was pretty saucy because of the bear-scene that was all over the news, but all in all I thought the romances were rather tame, added to the dynamics of the group and, at least in my case, were quite suitable to forward the story of Sava's journey.
As freshly broken-ups, the fight between Lae'zel and Sava about going to the Crèche in the Gauntlet of Shar in the midst of danger with Shadowheart and Karlach standing by in awkward silence, and then mending the companionship on the roof of the monastery while Gale and Wyll investigated the winery, was character-wise, while head-canon, one of the strongest turning points in the story, one that's still stuck in my memory after over two years.