Hmmm... I could give this a try. The effect (and thus the reward) could be enhanced by acting a little suspiciously beforehand too. A hint of perfume, lipstick on the collar, texts at odd times, mysterious meetings keeping me working late.
Then once shes realises that it's only another bike, and not an affair, then the relief will overide the purchase of another bike.
Pumpe, you're a genius!