Florence was super excited to hear that she was going to have an actual dad, however, Star wasn’t that excited. He not exactly fond of Rarity and Flo. He thinks that his family was fine the way it is and they don’t need another mom. Star’s little brother, Thunder Bolt, his happy with his new family.
Star Shooter doesn’t already like his mom, so he’s not sure if ready to trust Rarity. Lightning Dust is not allowed to see her kids due to an event that had taken place a few years before.
It will take him some time to get used to her. He doesn’t even like to call her his step-mom, he just calls her Rarity.