The entire Alleymates storyline, as far as its known. Out of the three images, 25333 was not on the booru at the time the archive was compiled, and had to be sourced elsewhere. None of the three images have a retrievable archived page of the booru. It could be inferred that the story is about an alleyway mare that is preparing a meal for her special friend, but a smarty comes, steals the food and poops on her. Because she no longer smells nice, she fears rejection. This interpretation however is pending confirmation from Carpdime himself.
It is also possible this series of images was an illustration for a story, but again, there is a lack of confirmation. Thus, this post is pending further information, whether its from Carpdime, other archivists, or a retrievable archive in future.
This short series was meant to depict stallions marking their territories to attract mates. Our green friend has set up a nice nest with shelter and access to food but Mr. Smarty swoops in and takes his prize. Poor guy.