Lisa: I have a feeling John is cheating on me...
Lia: Why?
Mary: Really? What happened?
Lisa: He's behaving strangely. 
Lia: Coming home late?
Lisa: Not that. He's ignoring me. He's been very cold to me.
Mary: Maybe he's stressed and doesn't want to share it...
Lisa: I don't know...
Lisa is worrying about John's behavior as he's been cold to her. She's afraid he may be cheating on her.