The fact that you're participating in the retreat (which is a great benefit to YOU and HER in the long run) is a "gift" in and of itself....however, if you're so inclined, get her a small token gift for her birthday. Nothing extravagent. A hand written note inside a birthday card and maybe a gift certificate for her favorite luncheon spot would be nice.
If you do the 'note' thing...don't grovel...just a brief expression like: "Hope you have a wonderful birthday, why not treat yourself and a guest to lunch while I'm at the retreat working on becoming a better man." short simple and it says a whole hell of a lot.
T2
