Serious mental health concern..

My boyfriend has schizophrenia. Or so he says. It's been a year since his last episode and I am wondering if it can just stop? I don't understand why anyone would ever lie about a mental illness or any illness for that matter, but this just seems weird. Before we started dating, last November, we were friends and he struggled a lot with it, and then as time went on, it just seemed to diminish. If anyone could give me any advice or medical advice on why this may be, that would be awesome! 😕