How cool! I'm glad your wife took that ride with you.
My husband wanted us to get into cycling together last summer, but on our first ride on borrowed bikes, I was miserable. The bike hurt to ride (the seat was awful!), and I couldn't muster any power because I was too tall for the bike. A few months later, when we were in Hawaii, we took out some cruisers (that fit us!) on a flat path that followed the coastline, and had an absolute blast. After that, I became more excited about riding again.
So my suggestion to put your wife in a position to enjoy cycling is to make sure her bike fits her properly and that her seat is a comfortable as can be. Then just have fun!