He's lost interest in everything else.
2 seconds sound clip from the Harvey (1950) movie soundboard.
You can hear this line at 00:25:54.929 in the Blu-ray version of the movie.
Quote context
[...]
- Now this person that you call Harvey, now who is he?
- But, uh, just who is he? Someone your brother picked up in one of these bars?
- Mrs. Simmons, if I'm not mistaken...
- Doctor, don't you understand? The rabbit's name is Harvey. Harvey lives at our house.
- Elwood buys theater tickets and railroad tickets for both of them.
- He's lost interest in everything else.
- Now don't ever tell that to anybody, Doctor. I'm ashamed of it.
[...]