Maybe out of left field, but if you consider Erryn as a LI and future ending for MC, what stops her from doing something equally stupid again after MC helps her clean up her current shit and they do get together out of pride or whatever?
Also Erryn does put a whole lot of blame, responsibility and hope on MC, if we remember that MC with their past basically owes her nothing anymore, she broke that the day of the confession and after plus staying friends with Ethan, which was her choice. Choosing against MC for her own reasons and wants, fair enough but that was her choosing her priority in relations.
In a way she is lucky enough he still cares enough to want to have some kind of relation with her based on his old feelings for her. Remember as he told Alexis in plane, he is not in love with her anymore and is not in a relation with her, let alone a confirmed relation.