The literature I read on it, from the doctor, 4 years ago said they'd need a booster in a few years and then another as a teenager.
Your wife was right, chicken pox is no big deal in most cases. I know when I had it there was no pain, itching yes, but no pain. And I've never heard anyone else ever complain that it was painful. The only serious risks I've ever heard of for it is bacterial infection when the sores aren't kept cleen, and the exceptionally rare case that it manifests in the lungs as a severe rash.
The numbers I've seen on mortality said the fatalities were under 200 a year. Even if all of those were in the USA that amounts to jack shit. What percent is 200 of 330,000,000? It's miniscule enough I can't be bothered causing my child and myself the discomfort of extra couple shots.
Nothing I've read indicates that the vaccine grants lifelong immunity. The fact that it needs a booster shot at all should be a clear indicator in that regard. The numbers I've seen seem to say it's more likely between 70 and 98% but it's hard to pin down because so much of it depends on prevalence of wild cases of chicken pox in the area.
The push for this being a mandatory vaccine seems to be a financial thing. If it isn't mandatory health insurance won't usually cover it.