Why doesn't he like any of my pictures on facebook?

This guy I was seeing for a while moved away. We keep in touch and talk pretty often, he'll always make comments on my pics on snapchat but I've noticed he's never like any of my pics on facebook. I don't understand, I saw he likes others girls pic. I know he is attracted to me because otherwise he wouldn't have been seeing me but Its a bit hurtful.
Why doesn't he like any of my pictures on facebook?
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