She’s harsh, but she does have Tei’s future as an actress in mind…but, she should consider what Tei and Ryuu have already gone through in order to have their love. They’d be able to put up with a bit of separation if they had it explained to them, the lack of honesty will just cause confusion and mistrust.
It shows her privileged upbringing, she doesn’t see or think about how much Tei would have had to endure already to marry a young noble. She’s treating her the way she would an average girl.