Twelfth Night Act 4, Scene 3

Sebastian wonders if his sense are deceiving him: does Olivia really love him? Is he insane, or is she? She does not seem to be crazy--she acts the part of a noblewoman well enough. He wishes he could talk to Antonio about this, but when he looked for Antonio earlier, he couldn't find him. Olivia comes in with a priest, asking Sebastian to prove he loves her by committing to her in secret. When he is ready to make it public, they can do so. She asks if he can agree to this, and he does.