My ex did something like that- turns out she was hiding a major illness. Her thyroid had gone into overdrive and all her organs shut down. She didn't see a doctor until a month after she left me, by which point she had lost 100 lbs, didn't have the strength to stand and was hospitalized. Part of the reason she left was because she was always the strong one and didn't want me to see how weak she had become. Another was that she couldn't continue to take deal with me (I was unmedicated and generally awful to be around) while fighting for her own life. Another reason was that the illness has a mental health component that clouded her thinking.

She came back eventually, but as we had other problems, she didn't stay.

I'm glad he has his mother watching out for him, at least you know that someone is, as he won't let you do it.

I'm so sorry this happened to you. It sounds like you love him very much. I hope he gets better and that you can be a family again.