My S/O is my permananent, and only dive buddy. We got certified together, and over the years have developed our skills together.
I'm lucky also, in that Jen is fit, athletic, intelligent and a great diver. She loves the sport as much as I do. Your first hurdle, and unfortunately one you can't influence, will be whether or not your wife takes to diving as enthusiastically as you did. As someone else mentioned, be honest about this with each other. Neither of you will have much fun if you're dragging her into it.
Assuming you get past that, just be patient and dive within your wife's limits. It took a year or two for us to really get in sync with each other, and for me to stop worrying so much. Keeping a hold of some of your anxiety can be a good thing. It will make you both a better, more aware buddy team, and thus, better divers. You two aren't that far apart in experience, and if she takes to the sport, she will catch up to you fairly quickly.
Don't forget that there are some great advantages to diving with your S/O. You always have a buddy. You can travel without worrying about being paired up with some nut case on the dive boat, and you know your buddy will be there for you in a real emergency.
It's also nice not getting hit with a dish when I go to the LDS for air fills and come back with a bag of stuff and a two foot long credit card receipt
Have fun with it!
Scott