When Regan finally emerges from Gloucester’s castle to greet her father in Act 2, Scene 4, she says: “I am glad to see your highness.” Lear’s response is:
Regan, I think you are; I know what reason
I have to think so: if thou shouldst not be glad,
I would divorce me from thy mother's tomb,
Sepulchring an adultress.
Lear’s suggestion here is that