Thoughts on use of another person’s email as a recovery option in Protonmail

You’re already using the feature designed for that purpose. I know you trust your husband, but you also have to think about the potential for malware or a social engineering attack where his account getting compromised would mean your proton would also. I’d also say you probably shouldn’t share passwords like that, I think most services where that would be useful let you share a subscription between multiple accounts.