I had to make an account after seeing this thread as well! I’m so glad to see that other people are just as disappointed in her endings! I accidentally spoiled it for myself and I honestly don’t feel like continuing. It’s like the happiness of having her be my partner was just yanked away. Why continue with her when every ending is either sad or bittersweet? I really hope Larian does something about this, like in a definitive edition or what not, but sadly I’m not holding my breath.
It's hard to even call it bittersweet when its forced upon you. As I've stated a few times throughout the thread and outside it, the reason we have multiple endings for characters is because they should feel deserved by our actions, and have their place in the story. Someone who pays no mind to Karlach is either going to see her tentacle it up, die or return to Avernus with Wyll (if they completed his quest but not hers), but someone who paid her the upmost care and/or romanced her is treated to the grand reward of... The exact same thing where a new option for the player to go with her is subbed in with the exact same other options. That's where it falls so painfully short in comparison to the lines of characters like Shadowheart and Astarion for example, who are affected by the player and the choices they make.
