I'm sorry, but we currently do not offer a family plan. Boxcryptor is licensed per user and if you and your wife would like to use all features of Boxcryptor Personal, both of you would have to purchase a Boxcryptor Personal plan.
To reduce costs, maybe Boxcryptor Free is sufficient for one of you. You can access shared encrypted files regardless of the Boxcryptor plan - given the other plan features are like max. 2 devices or 1 storage is enough.