、。
She's already quit her job, so we can't rely on her.
Literal
[topic-は] already job [object-を] quit [given-that-のだから], her [on-に] rely [thing-こと-は] cannot-do.
~のだから links a known/established premise to the conclusion drawn from it — stronger than ~から, which simply states a reason. Here it reads 'given that she's already quit (and we both know this), we can't rely on her.' The clause-final 頼ることはできない uses the formal potential ~ことができる, with は inserted as 頼ることはできない to add a contrastive nuance — 'rely on her, that specifically is what we cannot do.' 頼る takes に for the person being relied on. Reflects the practical reality of corporate Japan, where in-house favors and informal task-handling depend on someone's continuing employment status — once they leave, the channel closes.