Gumby (sorry for calling you Derek earlier),
As I said earlier, I can really relate to your situation. I am also a hopeless, passionate romantic. AND I have been in a situation that is very similar to the one that you describe. I won't try to hijack your post by describing the details of my own issues, but believe me they were strikingly similar.
When I tried to analyze the situation, I found that what I probably needed was the feeling of being in love again. "Being in love with love" is a cliché for that, I believe.
The reason why I am bringing this up again, is that I really want to challenge you to at least try to channel that passion back towards your wife. Looking back, I am almost surprised to see how well that worked for me. The thing is that the reward is priceless for both of you if you succeed. And even if you fail you haven't really lost anything compared to the situation as it is today.
Your other alternative, pursuing anything further with your young coworker, is much more risky (even when setting the ethical aspects aside), and I cannot reallly see a happy ending to that. You may end up hurting four different people in the process.