But that's still a rich wife, you either find a way to convince her OR you start stealing from her wallet every month for your monthly DCA activities.
If she has a large and expensive shoe collection, you could get one pair a month to sell in E-Bay. You could also hire your friends to kidnap you for ransom.
Stealing and kidnapping are not the answer. IMO building a strong relationship is about trust, good communication, and honesty. If your wife isn't supportive of your investment goals, the right approach is to have healthy conversations with her. Explain your reasons for believing in Bitcoin and the benefits of the long-term plans. If she is a supportive wife she will help out and if she insists on not helping, then you should find another alternative.