We got married without any expectation of sexual monogamy - "forsaking all others" was not in our vows. Instead we had boundaries that revolved around what we were comfortable with at that time in our relationship. At the time of our marriage (and indeed before) his "boundaries" included "no boys" for me. I boundary I had no serious problems with for 19 years - until, unexpectedly, I did. "Boundaries", like people, can change.
We were lucky enough to recognize before we go married, that society's "rules" for marriage were not necessarily the ones that we wanted to live by. We defined our marriage by rules that made sense to us - screw society. Not everyone has the benefit of exposure to alternative configurations/ideas before they tie the knot. They may not be aware of the fact that they DO have a choice (societal pressures being what they are) - so I don't think they can be faulted entirely for realizing after the fact that they do have options.
Tonberry - good point re: having children. When I married MrS I was aware of the fact that he didn't desire kids (he was 24 at the time - I thought this was entirely normal). I assumed that at some point he would change his mind, but was prepared for the possibility that he would not - not a deal-breaker for me. Turns out he DID change his mind - and we couldn't have kids anyway...
Point is - people get married (date, make friends, etc.) with all KINDS of assumptions/expectations. Sometimes they are WRONG. We live in the real world - sometimes we make mistakes. Should people who, at some point, realize they have made a mistake own up and admit it? Or should they "suffer in silence" and, possibly, sabotage any possibility of honesty in their relationships? Would you really want people to continue to lie to their partners about who they are and what they want once they have come to the realization that their marriage is based on a premise that they have come to realize is not actually true for them?
Yes - it sucks. It sucks for the partner who was led to believe that their lives would proceed in a certain pattern. It sucks for people who want kids to be infertile. It sucks to realize that your life has been based on a lie that you told yourself. Life sucks sometimes. At some point I think the best path is to look at where you ACTUALLY are and decide what is the "most honest" decision from that point onward. We can't change the past, the future is unknown, the most we can do is take the present moment and make the best decisions we can based on the available information. And sometimes those decisions SUCK. Sometimes we will make the wrong decisions, sometimes we will regret them, sometimes they will lead to happiness beyond our wildest dreams...
Me: poly bi female, in an "open-but-not-looking" Vee-plus with -
MrS: hetero polyflexible male, live-in husband (22+ yrs)
Dude: hetero poly male, live-in boyfriend (3+ yrs) and MrS's best friend
Lotus: poly bi married female, "it's complicated" relationships with Dude/JaneQ/MrS (1+ years)
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe