Hi,
We're all speculating a bit, because each case is different.
I don't know if this helps, but at one point my H felt like disappearing of the face of the Earth, and starting again. He didn't, as you know, but he explained how he felt so pressured by his life, that his life was not his own, and that something had gone wrong. As a perfectionist, it was unbearable not to have everything perfct. There were also a lot of things that he wanted for his life, and hadn't achieved (a common theme in ML I think), so this idea of beginning again was to address those dreams.
There are cases of vanishers who don't return ( I know of at least one), and those who do (I know one too). Do you remember the series "The Fall and Rise of Reginald Perrin"? He leaves his life by faking suicide, takes on a new persona, but eventually gets on with his life.
I suppose it depends on what they learn from their disconnection with life, and what they think they want. It's hard to speculate without knowing what's in their head.
I'm glad you're feeling better by getting on with your life!