Here is what that final shot in ending of Mare of Easttown finale devote almost as much time to exploring the fallout from the murder investigation as it does revealing Ryan as the killer and his motive. As devastating as the outcome is, the entire experience proves to be a cathartic one for Mare.
Throughout the season, the show slowly feeds the audience information about Mare's son, Kevin, constructing the backstory of a troubled young man whose mental health issues and drug addiction cause his family to implode. The circumstances surrounding his death become another mystery for the audience to unravel. In the episode's penultimate episode. Mare finally reveals her son hung himself in the attic of the family home and it was her daughter, Siobhan, who found him. Mare tells her therapist that nobody has entered the attic since Kevin's death, and it remains an off-limit space: symbolic of how Mare refuses to deal with her son's death and the guilt she harbors regarding her failings as a mother.
In the final shot of the finale, Mare opens the attic door and ascends the steps, signifying she's ready to deal with the emotions she's been repressing throughout the series. The show's director/executive producer Craig Zobel told Mare of Easttown explores how mental health issues can be ed down through multiple generations and the lasting consequences on everyone touched by it, the stigma attached, and the feelings of helplessness it perpetuates. Mare gains a better understanding of this during her therapy sessions which are the only times the audience sees Mare at her most vulnerable.
What seems to give Mare that final push is watching her best friend, Lori Ross, whose husband, John, and brother-in-law, Billy, covered for Ryan, lose her son. She sees Lori grieving, and the two make amends despite Lori's resentment toward Mare for arresting Ryan. This marks a turning point for the police detective. The dilemma facing all of Mare of Easttown's central characters is how they respond to tragedy. Although at times it feels like Mare can't possibly overcome the setbacks placed in her path, Inglesby told Variety that getting someone as "stubborn" and "tough" as Mare confronting Kevin's death was going to be a "hard-earned journey." The only way is to put her in the middle of a devastating situation that forces her to reevaluate everything and everyone around her, including how grief can become all-consuming.
Mare of Easttown's finale leaves many unanswered questions, and Mare's happiness moving forward isn't guaranteed. She's still grappling with depression, and whether or not Drew will inherit his father's mental health issues remains uncertain. However, as the show's murder mystery reaches a satisfying and heartbreaking conclusion, Mare of Easttown fans feel some satisfaction in watching Mare taking those first few steps toward healing.