It sounds to me like you have a good working rapport with your wife. If she's willing, why not take that one step further and become critique partners? A CP is someone to bounce ideas with, to get inspiration from and to help unstick when you're stuck. What could be happening when you get frustrated and stop writing is getting stuck in a "transition scene." If your wife is also a writer, she'll probably know just what this means. Not just for the story, but mentally in the writer. A transition scene is where you jump from one scene to the next. Where it becomes a problem is when you can't figure out
how to make the jump. You can have a brilliant scene that you love---the character just escapes death at an airport, for example, and in your mind you have another wonderful scene where the character saves all the people on a speeding bus about to crash into the bus station. But how the heck do you get your exhausted character from the airport to the bus station? What happens in between? You can't just have it be the airport bus to the hotel. That's too much. Something . . .
something interesting needs to happen in between, but not so interesting that it takes away from the airport or bus scene. But . . . what? <thumps fingers, twirls pen, wanders around and, and finally gives up and starts something new.>
Been there. Done that.
That's where a CP can jump in and toss ideas. Or, if you want to go one step further, you can make her a co-author and let her actually play with the text. That's a big step though. It would require you to consider the "kids" to be important enough to set aside your ego and accept that someone else can have as good an idea as you. Since you already acknowledge her skill, though, you might have to tamp down any latent jealousy you might harbor and take a deep breath. (And before you say, "But I don't have any!" really
think how you would feel if you handed her one of your unfinished books and she easily finished it. Would you feel elated and relieved, or would it bug the heck out of you?) Trust me, I've had to swallow that bitter pill. It can stick halfway down. But I decided the book was more important than my own hang-ups and allowed someone to fully re-work the text. Imagine my surprise when my CP fixed the problem! That's when my CP became my co-author for more than a decade. While we've now gone our separate ways, it was a terrific learning tool and I don't regret my decision at all. I know several husband/wife CPs and co-authors who write under a pen name, so it can happen.
Think about whether you can set aside the negative emotions that make a writer want to be the ONLY ONE to play with an idea. It might be you can't. Not everyone is suited to co-authoring. But if you can, it's well worth the experiment.