There are a number of beers that have very little hops taste to them. Have her try Newcastle. It has a slightly sweet caramel taste mixed with nuts, and with very little hops bitterness or aroma.
It's a very simple beer, sweet, mild, and not complex at all (much like a mild Riesling).
If this one doesn't work, have her try to describe what flavor she's getting that she doesn't like, and "aftertaste" is not sufficient. Have her try to equate it to other tastes even if they don't seem to make sense; pencil eraser, chalk, and sunscreen are perfectly valid descriptions.
See if you can pick out the same tastes now that you know how she describes it.
You being a more experienced beer drinker can maybe think of other beers you've had that don't have the same characteristics. Have her try those and follow the same process.
Keep a log so you can compare/review.
*** Most importantly, make sure SHE wants to do this. ***
Don't force it on her or you'll fail and she'll get upset every time you say, "hey honey, try this." If she is willing to go through the process, she may just find a beer she can enjoy (huge plus if you like it too).
Once (IF) she finds one she likes, have her describe what she likes about it and compare it to some of the others she hasn't liked. Look for other beers that are similar.
If you're stuck for beers to try, check out http://beeradvocate.com/beer/style
. Pick a style and start reading reviews of different brands.