If it's major/clinical depression, think of it as cancer. I certainly hope not, that goes without saying, but chances are your wife will have another episode. I was also fine for several months without meds, but the depression came back. Of course, your wife's and my depression might not be the same. That's the part that causes such confusion. There is no way to measure one's depression. Depression is sadness. Emotion can't be measured. So there are no guarantees. Your wife might never, and again, I hope this is the case, have another episode. But she might. That's why we prefer the term 'in remission', rather than cured, because there's no certainty it won't recur. I'm also currently in remission. But there're no guarantees it won't return in the future.

I understand she's your wife, if it were my wife, I would also want to believe there's a cure. But every source, whether it be therapists, psychiatrist, amateur blog, or research paper, says there isn't a definitive cure. Search online whether clinical depression has a cure, talk to medical professionals. I have nothing to gain by saying clinical depression has no cure. To the contrary, I'm admitting I myself will never be fully healthy. If I weren't 100% certain, I wouldn't be saying it. But if you don't want to believe it, nothing, no source, no professional, nothing will convince you otherwise. You'll always find a 'what if'.

Again, I wish you and your wife all the very best. Nobody should have to go through clinical depression. I hope she doesn't have another episode. But this disease occurs in waves/episodes. In between, when they feel fine, the patient is never 'cured'. They are in remission. However, with the right lifestyle changes, support system - like a concerned, understanding husband such as yourself - a purpose in life, and therapy to address the underlying problems, if any (such as childhood trauma/a crippling inferiority complex/a personality disorder, etc. - the episodes will become an annoyance, more than anything else.

I apologize for the length of this message, I found no way to condense this, and I hope you understand I have absolutely nothing to gain by being negative or arguing with you, neither of which I hope I'm doing. I take clinical depression extremely seriously. I wouldn't just say something without the proper research and experience.