Hi. Literally it means: "closed inside his office". It means that, beacuse of his sadness, due to the divorce, he concentrated a lot in his job, trying to work to avoid thinking to his wife gone away. Pay attention: it's "ufficio", not "officio".

Dopo il divorzio... chiuso nel suo ufficio means Gennaro thinks only to work, this is phrase is way to say typically italian. I put a elenc: Andare a catafascio means Andare in rovina. Andare a monte means Fallire, non raggiungere l'esito sperato Andare alla sbarra means Andare in giudizio, in tribunale. Andare in bestia means Infuriarsi. Perdere il controllo di sé, adirarsi, diventari violento Aver poco sale in zucca means Mancare di senno.( it is not clever )

always closed in this office