From thumbnail, I thought the left mare is Starlight Glimmer, makes sense this is originally GlimmerJack at first until I didn’t saw the included fic.
On the first day of Summer, Rarity takes the day off to go help Applejack tidy up her brand new cabin. As the two ponies finish up their work and share a laugh or two, they start to really examine their friendship and how they feel about each other.
Edited