Lis will definitely get Luna killed in a way or another at this rate.
I hope it won't have to go that for just for Lis to learn that black witches must not love nor get loved.
I'm still not convinced black witches are stricly not allowed to love, I need more details on what happened to the Green Witch's power after he had sex with the White King.
Wind Witch giving up is still on brand for him as while wind is persistent, it always follow the path of least resistance.
Even if adult Lis and Luna couldnt be together all the time for fear of interfering with their own respective powers, I still think they could get together periodically.
While you can argue that Lis is pushing his feelings one-sidedly, it's not like Luna has much other choices anyway due to her poison. Even if what she wants is the touch/affection itself instead of the person, it's still a good arrangement with net positives for both of them.
Lastly, while death isnt cheap in this story, it seems quite negotiable. Yes, I'm at the bargaining stage of grief.