What happened to, "For better for worse..."? Is this part of the old "Aisle, altar, hymn"? (If you don't get it, say it out loud.)
I presume she knew you were intact before you married her. It obviously wasn't an issue then, so why bring it up now? Is there anything else about you that she isn't satisfied with and will want you to change once you've been cut for her?
Changing things like your weight, fitness and drinking habits for a partner are one thing, but wanting you to make permanent modifications to your body is a lot to ask. I'd think very seriously about this before doing anything. At the end of the day, you should only do something like this because you want to, not because she does.
Plenty of guys who were cut as adults will tell you that their sex lives and orgasms are much better than they were before they were cut, but, by the same token, there are a lot of guys for whom the reverse is true. It's the sort of thing you can't really find out about in advance. However, one factor I've noticed is that many of the guys who are happier post cut had one problem or another with their foreskin before hand, such as phimosis or balanitis etc, whereas a lot of the guys who were less satisfied didn't.
You've got to decide for yourself what to do and why you want to do it. After all, you're the one who'll have to live with it, whether it's a positive, neutral or negative result.
You could always strike a bargain with your wife that she has a permanent body mod before you have your circ if that's what you decide to do - "Property of CuriousTom" or something like that, tattoed across her butt or on her belly. Would that be too much to ask? After all, she loves you, right?