Possible Clues:

• Social appointment with a stranger
• Social engagement (entered into with one's eyes closed?)
• New pairing of Venetian couple?
• Tryst with person unknown
• Social appointment between people who have not met before
• Did Len bat? Sent out in first meeting
• Appointment that lacks recognition
• Not a steady sort of meeting
• Love at first sight sought on this appointment?
• Social appointment with stranger