As long as you aware that the friend is imaginary, perhaps. If it gets to real, I'd say it is a mental illness.
Not sure if you can simply create that by willpower/meditation, though. Although it seems very likely that it is possible to deliberately fuck up one's mental health. After all, it is possible to fuck up one's physical health, too.
Not sure if you can simply create that by willpower/meditation, though. Although it seems very likely that it is possible to deliberately fuck up one's mental health. After all, it is possible to fuck up one's physical health, too.