Why doesn't Sal comfort Phoebe when she's crying in Walk Two Moons?

Answer 1

Sal was noticing that Phoebe's mother was really suffering from the neglect of her family. Her mom was reaching out to Phoebe, but Phoebe was just brushing her off. The entire reason she was crying was that she may not become a cheerleader, which seemed very self centered in the scheme of things. Sal asked her "In the course of a lifetime, what does it matter?" Phoebe replied that it would matter her entire life, but Sal thought that Phoebe should see that it was her relationship with her mother that would actually matter.

Answer 2

Sal feels guilty about not stopping her mother from leaving, so she is unable to comfort Phoebe when she cries because she is dealing with her own emotions. Sal is also grappling with her own grief and confusion, which makes it hard for her to be there for Phoebe in that moment.