Having gone through this process before, I'd highly recommend chartering a boat with a captain
for the first outing(s). That way, you can focus on taking care of your wife while someone else focuses on taking care of the boat. You'll all be happier.
Especially important if you're on an unfamiliar boat with her for the first time. Last thing you want is your stress (related to understanding and operating a new boat) to impact her feelings about long-term cruising and living on a boat.
Make sure to invest research
and effort into avoiding sea sickness
on those first trips. Nothing can destroy a woman's interest in joining you out on the water
faster than being sea sick. I speak from (painful) experience on this!