As we saw in the beginning of Season 1, Dan had spent several weeks after Roseanne’s death sleeping on the couch because he couldn’t bear to sleep in the bed they shared.
John Goodman makes some very good points about why being friends with Louise might lead him to reconsider romance with her.
So, not having anyone to really share familial responsibilities with must be even harder on him.
Dan has always been willing to do anything for his family, while also being open and honest with them, but he no longer has a partner to talk over decisions and difficulties with, and that has to make him feel even more lonely.