Honestly if it isn't deliberate I don't know what to say, but its been consistently sprinkled over multiple books.
Frankly, I just want a Suki focused book. Having it about her choosing between her loyalty to Zuko and her home or Sokka would be neat, even if it wasn't romantic. Zuko relies so damn much on Suki in the books it isn't funny. His reign would fall apart without her. She's pretty much been running Mai as an intelligence operative against Ozai loyalists, organizing household security and providing personal protection to the Fire Lord and his family, and providing a sympathetic ear for Zuko to vent too, easing his mental stress. She also never doubts his intentions or his ability as a ruler.
She's essentially his closest and most essential supporter. Even when everyone else thought he'd gone evil she held out and reserved judgement, believing there had to be a deeper reason for his actions, believing his intentions were good.