answer: Amy is so jealous because Graham is always on the phone with Jane and there was lipstick on his right cheek yesterday. Graham promises that he only loves Amy.
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.