At first glance, the fading image appeared to be a photo edit for a joke, but then I read the story.

This is indeed a bittersweet memory of a coffee cup.
There might not be any connection between the fading image of the cup and the fading of your relationship. However, if you do think so, maybe it's best to look at it as the relationship's natural progression. Somethings were not meant to last but we can cherish the memories.