I've never been too fond of Ash's character as such.... The reason being, she's never trusted Gunjan like Gunjan trusted her. For Gunjan, Ash is like a baby sister, but Ash has never viewed her like that. But I don't totally blame her for it, cause she's depressed, and frustrated. She lost her parents at a very young age, and Samrat was the only person she related herself to. When she found out about Gunjan-Samrat, her first reaction was that Gunjan took away the only person whom she liked away from her..... So you can see, she's frustrated, and her thinking isn't totally rational.
But yeah, she's been rude to Gunjan many times, like once she told Gunjan that she was interfering in her happiness cause her life's devoid of it, and she's jealous of her.... And I think she became very possessive about Samrat and hence, never really trusted Gunjan the way she should have.