Few things are better for Valentine's day than a painting by Jean-Honoré Fragonard, a French rococo painter who did a series of very sweet pictures - preferably of young men and women.
This painting is called 'The stolen kiss' and is painted sometime 1786-1788 and depicts a young woman who has sneaked away from her company (hinted behind the half closed door) to have a small encounter through a door. The girl's dress is typical of the time, both in cut and colouring.
It is a part of a series of paintings he did on the subject of kisses. The painting does not depict any named persons, but the face of the girl is very like that of Fragonard's daughter Rosalie (1769-1788) who was a favourite model of her father.
For a better look of the dress you can go here.
The painting can now be found at the State Hermitage Museum, Russia.