I’m guessing Rarity’s feelings toward Spike are…complex. As the Element of Generosity, she should be happy to see him make a new friend or even get a new romantic interest. On the other hoof, that’s HER Spikey-Wikey we’re talking about, and we’ve seen how Rarity reacts when people mess with “her stuff”.
@Background Pony
I agree. She was never into him, so I don’t know why artists sometimes depict her as jealous or heartbroken when Spike finds someone else.
I imagine Rarity would actually be pretty glad for this turn of events. She didn’t exactly turn jealous when Twilight ended up with Rarity-hair and Spike went googly eyes for the lavender one.