I don't think Meethi thought that Imlie was still stuck on her jeeju. I think she had seen a) Aditya's obssessive behaviour b) Aryan's love for her. She knew it even before Arpita c) Imlie's self-destructive bullheadness. She decided that only Aryan could protect her from a) and c).
Yes, he is! He's the only one who let's her argue her points and reach an informed decision. He was good at making her see logic till he lost his shit after the nightmare in the hospital