I looked at some of the posts you have made and I can see the position you are in (high school sweetheart wondering if there is something else out there).
I stumbled across this comment yesterday and it sounds like something similar to what you are going through (except she wasn't married yet): http://ut.reddit.com/r/relationships/comments/2la5n8/me_19f_with_my_fiance20_m_together_35_years_can/clt1fm3
It is interesting someone posting from your perspective because it really does show how the "grass is always greener". I have seen countless posts about people being jealous of each other’s pasts. They want desperately to be the only one that their partner was ever with. And yet, here you are, having that, but yet you still are not satisfied.
I think what you need to remember is this - no matter what choices you make in life, you will always be missing out on something. There is a trade-off for every single thing in life, and you will never have everything. Ever. People drive themselves crazy, ruin marriages, and ruin lives desperately trying to attain something that cannot be attained: everything.
If you leave your wife, you will be able to have a fun single life filled with as many women as you can handle. The trade off for that is love, mutual commitment, and being someone’s partner and teammate. At first things will be great and fun and new, but in time you may miss what you have now. And then sure, you can decide to begin a long term committed relationship with someone new, but then you will be in the same position you are now, except that you will have new regrets.
There is nobody on this planet who you will be able to have a long term fun, exciting relationship with if you are not a fun and interesting person! Maybe this unrest is due to not having a fulfilling life outside of your relationship. Maybe it is time for you (and your wife) to reestablish who you are, do fun things, and be individuals again.
It is the easy way out to break up and look for someone new, but that choice will lead to it's own compromises and trade-offs and. If instead you choose to work through this together, you will be stronger and happier than ever!