You might possibly think about addressing the issue of Rarity using Spike for favors all the time, so that it wouldn't look like she has an ulterior motive for having Spike continue to explore his crush.
That's a good idea. In my headcanon, in Rarity's eyes, she sees these favors and spending time with him as a way to teach Spike about hard work, art, culture and etiquette. She's unaware of how overworked he is. In fact in Rarity's eyes, she thinks she's going easy on Spike because Rarity when she was a filly had to do 10x the amount of work that Spike had to do in order to achieve her dreams. For Rarity, whose family used to be relatively poor before she her fashion boutique started to profit, she believes she's actually respecting Spike by making him do a lesser version of the work she had to do when she was his age.
But she's also a personal friend of Spike who actually sees Spike's comic books and video games as having a certain artistic merit and she likes talk to him about them especially the art design and characters. And Spike in turn learns about Rarity's favorite romance novels and shojo manga, that Spike is surprised he actually likes.
Though she can still be rather hard and judgemental on him to the point of stressing him out. She makes him do pretty hard tasks and even when talking about video games, she often tries to force him to play games she thinks have "artistic merit" even if Spike isn't interested in them and she even can get into Spike's personal life sometimes. Well that's where character development comes into play.
Basically Rarity is well intentioned but unaware. She's not the most emotionally empathatic and sensitive mare unlike AJ or Fluttershy.