I am only 24, have been been married for four years, and WE could have very well wrote that SAME letter. We have two daughters and a son. Coming from the female side, it's true that in Phase III, intercourse is the very last thing on my mind. When I am in Phase III, I feel like I have an obligation to fulfill (and I roll my eyes too), so my husband will be able to get through Phase II. At least this guy who wrote this letter knows it's Day 18. For me, my cycles range from 33 days to 40 and we abstain for about three weeks. I feel like the NFP teachers lied to us.
Since I'm super fertile (having had three children in three years) I take my temperature when my mucus patch starts because I am in serious need to postpone another pregnancy. And I am very strict about not having relations in Phase II because if I got pregnant right now I just might run away or go psycho.
I agree with this man's wife that maybe he hasn't romanced her enough. I totally feel like when that day of Phase III starts — I need to be extra-flirted with, maybe some flowers or this time he gives the kids a bath and puts them to bed. I feel this man does have an obligation to work at getting her aroused if she has such a horribly low libido in Phase III. Otherwise, it leaves us women thinking, "Oh great, Phase III is here. I have to fulfill my obligation to satisfy this out-of control sexual animal."