Surprise bitch, bet you thought you'd seen the last of me...
*ahem*
I encountered a bug or glitch during my third play through of the game while selecting romance options at the grove after party. A quick search told me that this issue one that at least a few people have encountered, so I'm going to add my report to that list as well in the hope of it getting fixed.
For context: this was an evil play through where I raided the grove, and I have already romanced and had intimate scenes with both Lae'zel and Astarion before this point.
During the party I talked to everyone and accepted all the propositions I could, including Minthara's, and then at the end of the night, when the narrator gives you the option to select your partner for the evening, I selected Minthara, only for the shortened sequence with Astarion to play instead (because I had already had his act 1 intimate scene). Then after, Minthara does her "good morning, now die" routine like she would normally do.
Being the save-scumming gremlin that I am, I immediately reloaded to figure out wtf was happening, and found that it seems to happen if I speak to Astarion AT ALL during the party. I could only get the Minthara intimate scene to play if I didn't speak to him.