@Yareyare
Why yes, preventing the numbers from reaching 0 is what the whole manga is about, so I don't get why you would ask about it now. I figured you were asking about what was shown in this chapter. What with her numbers disappearing as a result of their distancing.
Umi: My lifespan. Did it change? Were there any
positive changes?
Idiot boyfriend: Yeah. There was. When I passed by you in the hallway, your life span looked dimmer.
What he didn't mention is that it had dropped by 8 since the last time he had seen it. And if they separate completely, how is anyone to know if the numbers disappear or get brighter, if the numbers go up or go down since Rintarou is the only one who can see them?
The whole story is a bunch of hogwash, anyway, especially that dirtbag Itsuki's story. Rintarou's going to be the cause of Umi's death? How? For all we know, Rintarou could meet truck-kun and, not wanting to live without him, Umi commits suicide. Give me a break. Maybe Umi will die of lack of Rintarou because of following the dirtbag's advice and cutting her boyfriend off completely.