It wouldn't be very convincing if she buddy-ed up with Ilya at school and everything outside of card-collecting now would it? She's both socially awkward and logical. She's driving Ilya away from this world that she wasn't prepared for (and doesn't need to risk her life for), and this is the only way she knows.
She is upset (not angry) at the end of episode 07 (right before the credits) and gives the Illya household a curious (from my perspective) look before she enters her house at ep08 13:09. The entire exchange between her and Rin (particularly Rin's expression right afterwards when they were alone) points towards whether Miyu was okay with their relationship. All this would seem rather unnecessary if the main concern was about Illya's performance.
I'm sure Miyu told Rin and Luvia exactly what her intentions were right after Illya flew off crying in episode 07. Rin initially thought Miyu was being way too harsh, but has not questioned it since. Her expression at the end of episode 08 was one that shows "it can't be helped" more so than worry.
Miyu does things methodically. If she's decided that she wants to drive Illya away, she'll do it effectively and resolutely. She won't screw up (or tries not to) and go "tehehe, you found out" afterwards.
Back in Episode 07 or 06, Illya says she called Miyu a friend but didn't understand the weight that carried. It hinted that this is what Miyu would do for someone she acknowledges as friend.
I think at this stage there's at most a hint of envy, or none at all. Miyu was pissed after she saw Illya fly so effortlessly, but after she found out that such imagination requires no consideration or thought for reality, I think she decided that it was not pursuing. She's less of a "magical girl" than Illya, but after understanding her couldn't (and won't be willing to, I'd imagine) be an airhead to achieve it.Originally Posted by shinta