What evidence of Hamlet's affections for Ophelia exists?

In Act II, Scene I, Ophelia enters, distraught. She tells her father that Hamlet has frightened her with his wild, unkempt appearance and deranged manners. After Ophelia describes Hamlet’s behavior, she further reveals that, as per Polonius’ orders, she has cut off all contact with Hamlet and has refused his letters. Polonius reasons, thus, that Hamlet’s madness is the result of Ophelia’s rejection. He had thought that Hamlet was only trifling with her, but it turns out (he now declares) that Hamlet was indeed deeply in love with Ophelia. Polonius hurries off to tellClaudius and Gertrude that he has discovered the reason for their son’s odd behavior.