Idk... Feels like machi is super serious with acting but never got any role so she lost interest. She seems burnt out. Doesn't help that everyone thinks, or at least she thinks everyone thinks that childhood dreams can be so easily let go. Miyuri doesn't give a shit just like the others and it kind disconnect her with her friend at the end.
She only mentioned she didn't write letters for 2 years not like she didn't contact her for 2 years. I think it could be interpreted as she used letter to deliver this specific message since it's prolly a special surprise that she's returning?