That's sounds about Right(being a little more demanding). I think Im the same as your wife in that aspect. If there is no challenge Im not interested. Was like that with my other bf's not that there was so many . I don't see anything wrong with that. It will keep her on her toes so to speak. What kind of letter to her are you writing? I definately think when your ready you should send it, sometimes it is easier to write things down on paper then it is to say them, plus you forget things, at least I do.
Blessings~
me: 37 H: 44 Married for 18 years this june S7 S3 porn issues, and much more... since 7/06
Happiness can be found, even in the darkest of times, if one only remembers to turn on the light.
. I don't see anything wrong with that. It will keep her on her toes so to speak. What kind of letter to her are you writing? I definately think when your ready you should send it, sometimes it is easier to write things down on paper then it is to say them, plus you forget things, at least I do. 
