Deal breaker for me.
I think you’re misunderstanding me. There is no ultimatum, no threat, no assignation of blame, nothing like that. My husband and I simply have certain conditions that form the basis of our marriage, and it is mutually agreed that infidelity is not something that either of us will tolerate at any level. The reason for that infidelity is irrelevant. The extent of the betrayal is irrelevant. The question of who is at fault is irrelevant. The only relevant issue is that the trust between us, something that is hard-won on both sides for whatever reasons, would be completely destroyed. That single betrayal would put any kind of partnership or “teamwork” outside the realm of possibility.
In our case, and possibly in the cases of others who are calling infidelity a deal breaker, if you have reached that level of brokenness in a relationship the ethical decision is to end it. If my husband came to me and told me that he wanted to pursue a relationship with someone else, we would amicably but regretfully divorce. If he chose instead to sneak out and begin that relationship with someone else, he would have basically begun unilateral divorce proceedings in a much more dishonest, unethical way. This would apply if our positions were reversed as well. We understand that.
As Vihaga pointed out, having a condition like this in a relationship does not speak at all to the level of experience or maturity of the people involved. In our case, I think having such a clearly stated policy, if you will, about infidelity is the direct result of our considerable relationship experience and our maturity. We were in our 30s when we married and will celebrate our 20th anniversary next year. Our marriage has survived many challenges like those you mentioned in your post precisely because we are very clear on what we need and expect from each other. We talk about everything, even the hard stuff. It could be that understanding the high price of “a little interest from a 3rd party” makes us more likely in times of crisis to turn to each other for comfort and affection and support.
None of this in any way says that the way you and your wife handled your relationship crises is wrong or in any way inferior. I am sincerely glad that it has worked for you and I wish you continued happiness and success. Just try to keep in mind that it is not the only “right” way to have a happy marriage.