In order to protect the girl from being a widow, who is looked down upon by the rest of Nepal. If the woman's husband dies, she is still technically married to the sun and can hence not be called a widow, a tradition hence defying Sati Pratha imposed by the new-comers, rulers of Vedic lineage.
https://nepalfederalismdebate.wordpress.com/2018/06/24/master-list-of-all-nepali-surnames-clans/ https://www.indigenousvoice.com/en/why-jyapus-are-where-they-are.html Archived 2019-12-08 at the Wayback Machine http://ecs.com.np/features/preservers-of-newar-culture-jyapus-of-the-valley