When Sakura asked if the room was too cold, it dawned on me that Haruki wasn't heating the room. She wasn't planning for there to be an "After The Tenth Year."
I am so glad Kaede showed up.
I'm not sure, I interpreted it more as part of Haruki's general struggle to function as a human being after having lost Sakura, something we also see in her not eating properly. It feels more like a general loss of the will and ability to live than a real plan of proactively ending her own life.