Act II, Scene I: What does Claudio believe has happened with Don Pedro and Hero?

Borachio tells Claudio that he heard Don Pedro swear his affection for Hero and plan to marry her that very night. Once Claudio is alone he comments that it must be true since friendship is constant in all things except for love. He remarks, "Farewell, therefore, Hero" (2.1.160). Benedick arrives and invites Claudio to go with him, telling him the Prince "that got your Hero" (2.1.169). Claudio, depressed by the thought that Don Pedro has stolen Hero from him, leaves.