Dear Anon
Firstly I don't think "adequate" is good enough - but I have seen many an adequate marriage turnaround into a truly splendid marriage. You haven't mentioned if there is alcohol involved but somehow I have the sense there might have been. If so that would probably explain the problems you have noted in the beginning of your letter. It also could possibly provide you with either the solution or at least superior quality help for you and your wonderful children.
If alcohol has been in an issue in the past then a few visits to AlAnon (who help people whose lives have been affected by a loved-ones relationship alcohol) will make the world of difference. I myself went down that route to learn how to deal with my feelings about the person and I cannot begin to tell you how it changed my perspective and gave me back the power I had given away. There is also AlaTeen if your children are old enough.
Regarding the one-night-stand and the old flame, well that's a whole other kettle of fish entirely. Nothing is perfection - don't go searching for it, it doesn't exist. Yes general rapport and emotional connection are all well and good, especially after over a decade without it. But you would never consider eating your dinner on the same plate you ate your breakfast on unless you'd washed it in-between. So don't start dishing out your second meal before you've cleared up from the first. It is natural to sometimes feel like pulling the ceiling down around you in order to push yourself out of a rut but it's no good for you and it wouldn't be good for your children either.
You are correct, adequate is not good enough so see what can be done to fix it. You've said he has changed his behavior so why don't you try a few sessions with a Relate counselor to get you started on the right path. It would be a shame to throw away 15 years if there's a chance to fix it. Good luck!
