Is it permissible for a maternal uncle to kiss his young adult niece, and is this act considered forbidden?

The daughter of a sister is permanently forbidden to her maternal uncle by explicit Quranic text. The maternal uncle is permitted to look at his sister's daughter in the manner that is permissible for mahrams. It is permissible for the maternal uncle to kiss the head or forehead of his sister's daughter if he returns from a journey and does not fear falling into temptation. If the husband is jealous and dislikes this, the wife must obey her husband by refraining from such actions, while behaving gracefully to avoid problems between the uncle and the husband.