I can't get Dulrig's first heart even when doing everything during the mining trip, what am I doing wrong? What are the requirements? Does he need a certain amount of like?
I don't think we can obtain hearts from Dulrig yet. At least not in this patch.
Edit: I just found out we actually can. According to other comments, we can gain 1 heart from Dulrig by repeating the mining stuff with him a few times.
I ended up getting it after trying different things. I think you have to have fun with him, protect him, and share max emerine stones during the trip, but I usually had fun multiple times, so it kept him distracted and he was never happy with the end loot XD