I might try to talk her out of it.
I started with a mountain bike (1998), which I rode on paved trails as well as dirt. When I wanted to do longer road rides, I got a road bike (2002). When I realized a different road bike would be more comfortable, I got a different road bike and donated the old one to a nonprofit bike shop (2010).
I made sure I had the money to pay cash each time.
Bikes are not cheap and they take up space. I buy new jerseys and new socks when I want variety.

