Dear Brigitte (1965)

This being a mid-'60's movie, there are of some dresses/blouses that show some cleavage, but nothing excessive or particularly notable.

An older man and young woman sit together. The woman is wearing a dress that shows some cleavage, but not an unusually large amount. She is sitting normally in her chair, not bending over excessively as has been claimed. The man remarks, "You're overflowing with excitement!"

A couple are a painter of nudes and his wife, who he uses as a model. You can see her bare back from a long distance, nothing explicit is shown.