Because he was lying to her about everything, including his job.How does a college professor suddenly just disappear into thin air, and abandon his (not biologically, but still) child?
Not really? She basically just said to not impose on them all the time. The end of that chapter showed she cared about him too.The way this chapter portrays the Mom conflicts with how she was acting in the text messages in the earlier chapter, where she was treating him as if he was a nuisance to the neighbors.