Absolutely forget it ! You are going thru a questionable period.
I'm going to side with the previous post. Psychologically, the fidelity you have will be threatened. Like the previous person says, spice it up.
Try other positions, sex enhancer herbs, watch pornos together, get some spicy nightware, get her some sex enhancer herbs, (there is stuff out there that will HELP stimulate desire) vibrator for her or you, soft lights, pleasant fragrance, different types of stimulation,( check jackinworld.com for you and her), tieing her or you down, try longer foreplay, stimulating lubrication, make her orgasm many times. Make her have the best time of her life...she isn't a prude...she is very normal.
Mutually or solely masturbate if you have to...but don't wreck your marriage over a fantasy that might bring disappointment in itself. You got a good marriage...don't blow it!
I would guess just talking nice can really stimulate a marriage. The grass is always greener elsewhere....don't believe it!