Spend some time reading through the blogs and other posts. You will notice, those that have poly relationships that are working are putting a HUGH amount of effort on both fronts and still the emotions are all over the board. The balancing act is important.
If you truely want to stay married, I think you need to work on making that relationship the best it can be. Some of us find it easier to distance ourselves from people and keep from getting too close, which make it easier to walk away. This is not necessarily a good thing, unless you're a military brat.