If it’s half your money, say “no”, period. That’s what I did. Until she does her own research on the market, it isn’t your job to show her graph after graph attempting to prove to a nesting female that it would be smarter to wait. What’s she going to do, divorce you? (No offense to you nesting females – I love mine.)
I do recommend looking at similar properties on redfin.com, though. You can watch the price drops and see the sales history for individual properties, which can help it sink in.