I'm on va(stay)cation, too, but my visiting son is ill.
I wrote about this metaphor recently. Want2B, you and I have different writing styles(
) and don't always agree, but we agree on this.
I always thought I married up. My W did things I only wish I could do, and I always thought she'd find someone better than me some day, and I'd be abandoned.
In the few years before d-day, I saw that I did things she only wished she could do and that I was a top notch H, especially for her. On and after d-day, I decided/realized that I was a great H for her and that, with all our weaknesses, we were a great match for each other.
For me, the real why for her cheating was her totally undeserved self-hate. She saw herself as a horrible, unredeemable person. The world was treating her as if she were a good person, so she showed us who she really thought she was - she cheated in an especially harmful way. I always saw some of that darkness in her, but I didn't realize its depth. I felt very sad and perhaps some anger at myself for not seeing it, but I knew I had done my best.
IOW, I saw her A as a symptom of something like an illness. I knew I could leave, but I also knew I had vowed, though not in so many words, to stay through illness. Besides, we were both better people with each other than alone, and I still lusted for her.
I took no responsibility for her A. I hoped she would cure herself, but I knew there wasn't much I could do for her - this was work she had to do for herself. On d-day, I knew the A just wasn't about me.
I adopted the 'shit sandwich' metaphor in some early posts, but I really don't see it as useful for understanding R or infidelity.
The metaphor may have some use if one stays only because of kids or finances, but I wouldn't call that R.
I'm not saying it's wrong to apply the metaphor to R. I'm just saying if you think you have to eat shit to R, I think you'll have a very hard time.
Remember: neither D nor R are useful goals after a d-day. The most useful goal is to arrive at the decision via taking responsibility for oneself and making the best mindful choice one can.
In reading this post, note that everything that isn't sharing my experience and thought process is just plain opinion. It's my honest opinion, but that's all.