Alice knows Bob well but doesn't care for him. And at times she treats him callously, with pranks that go too far or simply not giving due consideration. Alice most likely does not realise what she's doing; Bob simply does not register on her awareness of others.
Then one day Alice goes too far, and Bob snaps at her. The result is a loud, dramatic slap and he storms out. Alice is stunned at [...] [tvtropes.org]