Interesting. I've had nothing but approval from Shadowheart, and lots of it. Killing Laz'ael no doubt helped. Our approval reached "very high" well before I reached the party scene. There was an option in dialogue with her to say how I regretted we hadn't had a chance for a deeper connection, and she responds with a desire to get together later and have a private sexual encounter. This was well before the party scene, so when that rolled around I just assumed this was our sexual encounter and not just sharing a bottle of wine. Certainly all the companion dialogues and my options indicate this is at the level of physical intimacy. Now the moderator tells me, the romance is supposed to be a slow burn. This is either badly written or the script doesn't take into account that you can bond with Shadowheart very early.