I gotta say, everything I've read about Karlach's supposed endings is just bleh... disappointing... and I haven't even left ACT 1 yet. For an Origin character which was not at all playable during Early Access, she captivated me in an instant and made me instantly pursue her as my character's primary romance. I think that says a lot about how great of a character she is.
So hearing how this story supposedly ends is seriously disappointing, because it feels like they've written her like this; "Oh Karlach is radiating too much of a positive vibe so in order to balance it out lets give her some shitty ending where the player cannot have her, to provoke some emotions".
In DOS2 all characters had such heartfelt wholesome moments and epilogues despite their past hardships... such wonderfully complex characters, so I expected nothing less for BG3, but unfortunately the more I'm playing the more it just feels like a more polished but not-fully-thought-out Early Access that is still hoping to jam stuff in and change/rewrite them on the fly.
The game's really fun and great, but it sucks that I'm gonna have to wait till the Definitive Edition to fully enjoy all the dialogue branches fully optimized with proper outcomes that should be here right now.