That’s the thing about depression is you can still function in society. Look at Robin Williams, Chris Cornell, Curt Cobain. They all suffered with deep depression that eventually took their lives, but they still “acted” normal. Colm Doherty continued to act normal so that people wouldn’t suspect that he’s in a dark place as he doesn’t want them coming to his house. The village was so small that someone would always come check on him and that’s why he would get angry at Padraic who kept coming.