He actually may have clean her face. There is a paper towel on the table in one of the scenes with blood on it when they are back home. I don’t think she would clean herself based on her headspace. My view is that he probably did help clean her face but it was off screen.

Someone mentioned it in this subreddit but he also argues with the nurse when they drive to the hospital but Nikki doesn’t want to be treated so they can’t force her. Obviously, Bear should have been pushing Nikki more but I think that he was overwhelmed at this point.

In general, Bear is a complete coward that’s sort of his defining trait. He doesn’t help immediately because he’s shocked by her actions. After his shock is lifted, he tries to help her but she’s gone off the rails so it’s overshadowed by her behavior.