1: i think you can find him again in the wolves den at night and you need 5 ~6 werewolf lure to capture him.
2: I think we dont have any way to romance with Naxaus until now. And about Rhot you can have sex with him, you must complete Lizard story line with good ending and then talk with Rousk about Bareshade then buy a Diabosite Spear, give it to him and rest at the shrine ( at night ). He will come visit you and after that you can ask him about night visit. Rest at shrine again and you will able to have sex with him .
I hope it will helpful for you 😁😁