The only one

Elizabeth ate slowly. Seeing her finish eating and putting down her chopsticks, Leo asked her, "Do you want any snack?" "No need. Thank you." "Okay." He nodded and then pressed the calling button on the table. Soon, a waiter came in. Looking at him empty hands, Leo frowned slightly and asked, "Where's the thing I asked you to prepare?" The waiter apologized and said, "I'm sorry, sir. It hasn't been delivered yet." Leo checked the time and was a little displeased, "Why are they so slow?" "I'm not sure. Maybe there's a delay on the way. Can you wait a little longer?" Instead of replying to him, Leo turned to ask Elizabeth, "Are you in a hurry to go home?" Elizabeth also looked at her watch and it was already eight o'clock. "It's about time to go back." "All right." He shrugged gloomily and said to the waiter at the door, "We won't wait. Bill, please. Thank you." Then he took out his wallet. Before his card was taken out, a man's voice came from the door— "I'll treat you!" Elizabeth looke