This is Henri Toulouse-Lautrec's "In Bed", as the Musee D'Orsay calls it.
Since I first saw it (at around 14) this has easily been one of my favourite artworks. Well into the top five. So I went and paid my respects, much as I do to the Botticelli Mars and Venus every time I am in London.
Being in love with a painting is as mysterious as love of anything else, but I will have a go at explaining why I think this is so great.
Firstly, it is fresh in technique, composition and subject matter. Previously I have said that I think originality in painting is over-rated, but a new vision has a place - Lautrec painted what he saw around him (like the Impressionists before him) but the world he created for himself had not been considered a fit subject for painting before. This world has been a favourite of teenagers (who identify with those on the outskirts of society) ever since.
His compositions and colours are unlike those of official art and work hard at looking careless and unposed - a stratagem that is aided, oddly, by the artificial poses that his performers like to strike. This one, however, comes across as a snap-shot - despite taking half an hour minimum to paint (and likely much, much longer) as well s working in various compositional techniques, such as the placement of the center of interest. Much of it is very sketchy - but like all truly great works, nothing could be added or subtracted without lessening the work.
It is nothing less than a painting of love - any two people who have this kind of connection are among the blessed. Here is sex, trust, honesty, familiarity, warmth, joy - all from one and a bit faces and a crumpled bed!
There is ambiguity, too - are they two women, two men, one of each? I don't care and do not think it matters.