Characters
Give him the date for when Mary’s out of mourning. No one wants to kiss a girl in black.
— Dowager Countess · Downton Abbey

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker asks for the date on which Mary will be out of mourning to be passed along to him. The reasoning is brisk and unsentimental: a girl still dressed in black holds no romantic appeal, so the period of grief is treated as an obstacle to courtship.
Context reviewed