I thought this only happened in cartoons

I am sure you've seen this story about how a man found out his girlfriend was cheating on him when the parrot started saying things like "I love you Gary" in his girlfriend's voice. I mean everytime I've tried to get a parrot to repeat what I say it just gets mad and claws itself away from me. Here, she says something on the phone with the bird in the room and he repeats it? On another note, I understand that the relationship wasn't going well, but why still live there if he talks to the bird more than you?