Of all the guys I know who have ended up divorced through aviation, the origin point is often an already poor relationship exacerbated by time away from home or another pilot or flight attendant got between the sheets. I've never once seen or heard of a relationship which was strong end because of aviation. In saying that, a pilot who jumps ship every two years to get on the next bigger, shinier airplane may be sanding down their relationship due to financial concerns.
The rate, I'll agree, is way too high. So high in fact that here in Canada (and I'm sure elsewhere) we have a term for it: AIDS, or Aviation Induced Divorce Syndrome. Bad taste, I know, but...
Perhaps this divorce rate says more about us in a general, disposable society frame than a group of aviators.