Maybe Hato and Ruri can curb the other's overworking tendencies?
I like this idea, and I also think that at least partly that's the angle here. The way I read it is that Ruri is really burning herself out, for one reason or another, and with how Ruri's dynamic with Hato has developed, I feel that if there's anyone that will really see behind the facade and/or to whom Ruri will truly open up, it'll be Hato. In other words, I can see the two serving as an anchor for each other, as the comment I quoted says.
Also, there's something I find adorable about how Ruri seems to have just immediately gotten attached to Hato and has made her a regular part of her life/routine. Especially as shown in this chapter, she even knows about Hato's routine. I find it all adorable.