If your wife has a favorite color find the closest match on weber.com and say it is because she loves that color.
Honestly, I have probably purchased 9+ grills in the past year and a half (some of them keepers, some to trade, some for parts) and I would probably have more if it wasn't for all of this COVID-19 stuff slowing me down from finding vintage. Tell them you got a good deal, that it is rare, that you couldn't help yourself, and etc.. Honestly, everyone has their own hobbie/thing that spouses tend to have to accept it in my opinion. Just make sure you are doing what you can to make it up to them for your hobbie/thing.