The Progress of Love: The Meeting, Jean-Honoré Fragonard
Link is to zoomable image on Google Art Project; high resolution downloadable version on Wikimedia Commons; original is in the Frick Collection.
This was part of a series of four large paintings depicting four stages of love. All four, along with several smaller canvasses, are now in the Frick Collection, which has special a Fragonard Room devoted to them.
Link: The Progress of Love: The Meeting, Google Art Project