answer: Amy is jealous because Graham is always on the phone with Jane, and there was lipstick on his cheek the other night. Gramham tells the reasons to her and then Amy believes in their love.
documents: #Person1#: Graham, why are you always on the phone with Jane? 
  #Person2#: Because we are partners in our science lab. Why are you so jealous? 
  #Person1#: The other night when you came home there was lipstick on your right cheek. How do you explain that? 
  #Person2#: My aunt Mary just flew in from Cleveland and she laid one right on my right cheek. 
  #Person1#: Are you sure? 
  #Person2#: Of course I am. I only love you, Amy. 
  #Person1#: Okay, I'm sorry. I believe you. 
  #Person2#: Why do you always accuse me like that? 
  #Person1#: Because you are the most handsome boy at the university and I love you so much! I guess I just go crazy sometimes. That's all. 
  #Person2#: Oh, Amy. I am the luckiest guy in the world. 
  #Person1#: Why? 
  #Person2#: Because I am loved by the most beautiful girl in the world! 
  #Person1#: Oh. Graham. I love you so much and I really believe in our love.