If you are seriously in debt I can understand your wife's reasoning, and in fact if you are in serious debt you probably should be looking for a used bike.

If you aren't in serious debt than it sounds like you and your wife have serious issues when it comes to you wanting to have hobbies of your own.

My wife and I don't pester each other about the other's spending habits, we have our monthly bills to pay, but are debt free, so if one of us wants to spend his or her money on something all the power to them. She does have an issue with all the bikes and frames in the garage though.....