Another thought:
I was preparing for a big trip and I was working on a battle plan for shmiras einayim on the trip (posted at
www.guardyoureyes.org/forum/index.php?topic=2665.0). While in general, I don't think my wife wants to hear too much about this subject and would rather pretend the issue doesn't exist, I did not think it was appropriate to spend so much time (especially on the computer) without explaining what I was doing.
Of course, I phrased the discussion in context of what we see in the street, not the depths of the Internet (or worse) and she was in general was appreciative and supportive of my efforts. At the end she asked me, "why is this such a challenge? Haven't you been there done that already? Shouldn't it get boring?" I told her, "I don't know, I didn't create the world" and left it at that.
a. I would like a better answer to give (if anyone has one).
b. While she didn't phrase it that way, I suspect some of the depth of her question was, since I have seen her in all her glory, why is what's on the street more attractive? Are they some much better looking? (i.e. Do I not appreciate how she looks?) Which highlights [one of] the concerns of discussing this with our wives (even in a very positive context).