Does anyone know of anybody that has, per agreement, stepped up & married their best friend's widow, without having crossed any lines prior to that death?

My grandfather and his best friend made such an agreement back in 1949. They were both socially-outcast deaf men; Grandfather had 3 hearing children with his deaf immigrant wife while his best friend had never even dated a woman.

The following year, late 1950, my grandfather was tragically killed. His friend kept his promise & married my grandmother on Valentine's Day 1951, and they had a daughter together in 1953.

While I personally see nobility and humanity in the agreement & subsequent upkeeping of it, I really don't see such a thing happening on this scale, in this day and age. Anyone have or know of any other examples?