...So, Vlad... do you approve of those policy statements from your bank/whatever that say "we reserve the right to change these rules to our advantage at any time and hold you to them, whether you like it or not'?
Because that IS what you're arguing - that any partner to a contract has the right to unilaterally change the rules at any time. Now, assuming that this was one of the common marriage ceremonies that uses the phrase "cleaving only to each other, so long as you both shall live," then that is a pretty definitive contractual term that should ONLY be altered by an agreement of both parties (and I have acquaintances who HAVE made those arrangements - but BOTH PARTIES AGREED to the amendment!).
Now, you seem to believe that if one partner is away for a year, the other has the right to look elsewhere for sex. Now, what's the LOWER limit? I mean, obviously, he was away for LESS than a year when she started in with her "bowling buddy". So is, say, six months a reasonable lower limit for you? How about three months? What if she couldn't go for a month? Is that okay?
Suppose - assuming that you ever find someone to marry you - that you know that your spouse can't go three days without sex, and your boss sends you out of town for a week... You will, of course, be understanding if you find your spouse and the plumber testing the shower together when you come home?
Finally, regarding your comment that, "Maybe, just maybe, Tony hadn't used the services of any local sex workers during his tour of duty (although I doubt it very much)...", I draw your attention to the words of George Bernard Shaw: "(A pessimist is) A man who thinks everyone as nasty as himself and hates them for it.”