There probably is never going to be a cure, But there are ways of working on your stammer. Your fiancé just has to figure out which one works for him. I found my salvation with the McGuire programme. A therapy by stammerers for stammerers. I have been working on my speech for 4,5 years now, and it has really transformed my life. It is not a quick fix, and you have to keep working on it but it gets fun after a while and that keeps me going. The McGuire programme is a world wide organisation.