Can't meet, they miss each other. But once able to meet, once again walk together, they will torture each other again.

不能见面的时候，他们互相思念。可是一旦能够见面，一旦再走在一起，他们又会互相折磨。

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The strolling man and woman mentioned in the title are easy to miss, but once seen they add an unmistakable note of foreboding to the composition.

WSJ: Vincent Van Gogh Up Close | Philadelphia Museum of Art | A Matter of Perspective | By Jonathan Lopez