Sue & Don
STB:
Of course We each have our own way of justifying the way we live and the way we think all culminating in what 'turns us on' as an individual. You know what turns you on and you 'seem' to know what 'turns Sue on'. Of course I am a 'third party observer' and can only analyze what I read in your thread. When I try to put myself in your position or step into your shoe's so to speak, I believe I would be much more comfortable being more closely involved as in being with Sue more often when she is with Don (or any other lover) I not only know I would be more comfortable, but I believe the wife (Sue in this scenario) would feel more comfort and support from you her husband and would be less likely to "run off" (as we now see a 4 hour drive + time with him with little chance for you to intervine with her decision) Or, as you acknowledge a fear of, Her "running off" with a lover for a much longer time (also without your objection).
STB, at this time it would have only taken a "I would rather you did not go" to stop her. The more times this happens, the less likely you will be asked. I just think by then it won't be much of a "turn on" anymore.
Sorry, But I just worry that: 'thinking you have good communication and therefore a good marriage' is not as good as good communication and togetherness in a marriage. The less intimate time she spends with you, and the more with a lover (with or without your consent) will, whether you see it now or not, be the end of the good communication and the good marriage.
Just my opinion!!! As I said, I am not there to observe. (only as a third party reader) But I seriously worry for you and I am not alone!!
Cheers, Harry