Man, you're your own person. I realize that there will be fallout afterwards, but sometimes you just gotta do what makes you happy. I think she'll probably get over it in time and a few months down the road it won't be a big deal at all.
"Hell hath no fury like a women scorned." Shakespeare The Taming of the Shrew. For all those responding about growing a pair and what type of panties I wonder if you are either still single (I wonder why?) or divorced.
I noticed the OP has only 4 dives in year since certification. While the OW cert allows you to dive without an instructor we have any number of threads on SB about diving within your training and experience. It's the experience that your wife is concerned. It would also depend on the experience of your buddy. If your buddy has several dives, is very experienced then your wife would be over-reacting. If your buddy also has 4 dives then your are basically diving with another newbie and that is not necessarily the best combination.
Just to play devil's advocate, if you simply said that you have only 4 dives since certification and would it be a good idea to hire a DM as your dive buddy I'm sure nobody would have made any comments about who wears the pants in the house. You would have received a bunch of yes that would not be a bad idea responses. If you said your dive buddy also has only 4 dives then you would receive many more the two of you should at least dive with an experienced diver or DM responses.
Personally, with less than 20 dives total I was taking my daughter on her first dive since her certification in the tropics on vacation. We were going to dive locally in her first cold water dive in a wetsuit and hood, and in a location I had never dived. I opted for a DM in large part because I didn't think I was qualified enough to supervise her if something went wrong. Imagine that conversation with the wife. Fast forward, we both have AOW certification and don't dive with a DM anymore. In fact, we are planning our vacation dives in Maui this summer and she now has the training to do the Carthegenian wreck at 90 feet. She sat out that dive the last time we were in Maui because she didn't have the training.
I'd rather dive with a DM to start, get the experience, then start to wean myself off the instructor's leash. Get some more training, just get some more dives, and I'm sure the wife's angst will also improve as your skills improve too.
For the record, I'm going on 18 years this June.