"But it wasn't enough for you. You were distracted by your own desires: bloodlust, murder, chaos, and most damning of all, an unexpected weakness, and longing for acceptance and affection from a mortal."
I can't post the gifset from tumblr because the images are too large, but I am going insane over this dialogue from Minthara's torturers at Moonrise Towers if you romance her in Act I. First of all, knowing how Minthara prizes the sanctity of her mind, this kind of mental torment and digging through her most private thoughts to torment her with them must rank among her worst-case scenarios. Second, that it's not her violence that's being used to most condemn her, but her desire for affection, her yearning to belong. That is what's being called out as her greatest failure--and that probably tracks perfectly with what she was taught in Menzoberranzan. That when she finally tries to reach out anyway, in spite of knowing this would be considered weakness among both the drow and the Absolutists ("I wanted this, for myself" she says to you after your night together), it's used to punish her. It's no wonder you can't just pick your romance up with her where it left off when she's just been so brutally reminded that love or even a semblance of it is a weakness that can and will be used to hurt her.
There's also the fact that if you kill her in Act I and then speak with her corpse, you can ask her what her "ambitions" were before she died, and she tells you "To find a home." Minthara is LONELY and I will stand by that.