Look some ships just come out of nowhere and I can't give a full explanation to why I ship but I do :' D
I'll try tho.
Sunset has been visiting Twilight more often as of late because she's contemplating on moving to Equestria permanently. Her EQG fan group were all going their separate ways and Sunset didn't feel at home without them around. (They still visit eachother monthly to see how things are and such.) In Sunset's visits she stumbled upon Skystar more then once. At first she didn't give the hippogrif much though, but then one day Twilight decided to drag Sunset to visit Mount Aris to accompany her for a meeting, Sunset found Skystar in the gardens with a clear upset expression on her face.
Sunset didn't want to leave the burd there alone to mull over her feelings. So she said hi and asked what was wrong. Skystar saw Sunset and released a big sigh. They talked and talked. The more they talk the livelier they got, it wasn't long before they started to exchange letters and became active pen pals. Sunset didn't understand why she was all of a sudden to excited talking or receiving letters for this hippogrif. Every letter made her heart flutter and when she read them she couldn't help but feel all warm and fuzzy inside. Silly she couldn't be in love could she? Sunset likes the nerds and sophisticated type, not a big……fluffy….sometimes funny…silly..burd- uh oh.
Skystar made her nervous, giddy, she even made her twiddle her hoovesies on the ground once, which she never did. How can this hippogrif princess snatch her heart so quickly? Sunset didn't think that she had a chance with Skystar because Skystar was really into boys. Her letters would usually be about boy problems or the mini crushes she would have over the weekends. Sunset would help and gave Skystar continues encouragement eventho it broke her heart a little. Maybe just maybe you like girls Sky? No no that's too forwards, does she know I like her!! Oh gosh this is so stupid, I can't get her out of my head.
Skystar's not aware of Sunset's feelings towards her, but she does enjoy Sunset's company a lot. She looks forward to her visits and letters as much as Sunset does. She loves to snuggle, but she likes snuggling with Sunset the most she doesn't know why tho. Skystar notices how tense Sunset is when she comes close for a hug, and how her breath hitches when Skystar buries her face in Sunset's mane to smell her conditioner. Silly burd getting a bit too personal there.
Sunset hopes that Skystar knows how she feels at some point. Maybe then she won't get all flustered when Skystar cuddles up next to her to keep warm. Oh dear, Oh my.