fatespeaker x Starflight isn't cannon and as well it is shown that fatespeaker doesn't care of what Starflight wants only of what she wants and if you look at the chapter book 5 of wings of fire near the end it says something about how sunny felt jealous that fatespeaker was near Starflight.
Starflight x Sunny is cannon and it's shown that Starflight is in fact in love with sunny cause he literally confessed to sunny and sunny is confused since she's never felt this feeling before so I think that's why she told Starflight she loved him as a brother to the fact they aren't siblings and plus fatespeaker and Starflight barely know each other while Starflight and sunny have been with each other their whole lives since birth.
