Here is how I did this:
1. Break your ankle in such a way that it requires emergency surgery on a holiday if you ever plan to walk again.
2. Show her the off-the-rack $10K+ specialized and Trek bikes.
3. Then show her one of these:
https://caletticycles.com/bikes/
Of all my gratuitous purchases, this one was by far the best-justified five years later. Besides, compared to sending the first of three kids to college, it was spit in the ocean.