IPA: //ʌnˈdjuːtɪfəl.nəs//
KK: /ʌnˈdjuːtɪfəl/
The condition of not being obedient or failing to fulfill one's duties or responsibilities.
His undutifulness towards his family caused a lot of tension at home.
Undutifulness → It is formed from "un-" (meaning not), "dutiful" (from "duty" which comes from Old French *deu*, meaning owed or due), and "-ness" (meaning the state of being). The word describes the state of not being dutiful or failing to fulfill one's obligations.
Think of 'not' ('un-') being combined with 'duty' to remember that 'undutifulness' means the state of not fulfilling one's duties.