Astarion Romance & Nightsong

I’m trying to get all the romance scenes for Asterion. I’m currently in Act 2. I killed Yurgir and I’ve done all the trials in Shar’s temple.

I haven’t saved the nightsong yet because I’m seeing conflicting information about it. Some say it’s fine and won’t affect asterion romance and some do.

Does anyone here know how that game mechanic works?