This, too, has been one of the biggest hurdles for me to overcome. When I said forever, I meant it. I took my wedding vows very seriously.
My clergy reached out to me saying that he could sense something was "off" with me, that I just didn't seem like my old self anymore. We went out for coffee and a three hour deeply theological and philosophical discussion brewed :-)
He explained to me that, in his opinion, God never intended for us to be miserable. Like people, relationships can die. "Til death do us part" includes when the relationship is broken beyond repair. In the case of an unintended MOM, when the straight partner realizes that they were duped and that the foundation upon which their marriage was built was a lie or at the very least an error of omission, often times that is the death of the marriage.
I was anticipating a judgemental position from my clergy, one that might infer "I didn't try hard enough" etc. But instead I was met with great compassion and understanding, and a promise of love and support within my community of faith as I progress through my own journey.
Having spent so many years internalizing these things, I have tended to beat myself up over the things for which I had no control. I often looked at myself like the proverbial kid who's mother had to tie a steak around his neck so the dog would play with him. I have been starved of love and desire throughout most of my marriage and have always been made to feel it was all my fault. I was too fat, worked too much, too angry, too depressed, not fun enough, <insert every other excuse here>, to be desired. I have for decades felt that I was somehow undeserving of true love and affection. Now that I have finally learned the truth, I am resentful that my wife could so easily overlook my feelings in order to achieve the picket fence nuclear family facade that enabled her to lead the life she wanted to project to the world.