You already had some good suggestions, but I'll throw in my two bits and see if it helps. As someone else said, what are you grilling on? Gas is convenient, but I believe charcoal produces more flavor. Can you list what is better about the steaks you get out? Are they juicier? Are they cooked more evenly? I don't think you need to change how she likes her steaks, I like mine well done and can barely tolerate medium well, but you still can have a good steak that way. I've had some problem with steaks continuing to cook after I take them off the grill and ending up more done than I want, so now I try to pull them earlier.
There is no reason this shouldn't be a solvable problem if you are willing to do some experimenting. First we need to get some examples to look at, so go cook some rib eyes and take pictures. Then lets cook one different, if the first one was cooked over gas, cook this one over charcoal. I like steak cooked on the stove in a pan, it has a nice sear and tends to be juicy, try one that way. Next try a marinade, or if you usually marinade go without it and try a dry rub like Montreal Steak Seasoning. Then there is the grade of meat, cook one you normally buy, then buy a steak from another store, maybe a higher grade, can you tell a difference? Maybe it just comes down to steaks from one store tasting better than those form another store. If you are willing to try cooking steaks a bunch of different ways, I'm betting you'll find one you like. This may result in lots of left over steak, well they are great chopped up for chili or slice and make Philly cheesesteak sandwiches.
