A difficult one. Do you think she knows why it is such a hot thing for a bloke? I have always assumed most women know that we poor men have our g-spots up our @r$es but my wife's a doctor so I didn't have to paint any pictures when I asked for this which was a big help.
Only you can judge if your OH has already heard too much about the topic but if you judge she hasn't perhaps it would do no harm to make sure she really does know what you are missing out on.