"MrBond, my question is what is the source of the assumption that "sticking with that one person" is a stronger "vow" than being a sexual partner to your spouse?"
All of this is semantics. They come down to individuals and their own perception of what M means, not necessarily the "vow". The vow includes things that also include things that don't include sex. The fact that you're going to be with each other through thick and thin, sickness, poverty, etc. It's about commitment to be true to one another even when the chips are down.
Some people believe sex is part of that and some don't based on the wider scheme of things. If a spouse is injured or gets old and can no longer perform sexually, the vow is there to say that you are committed to one another no matter what.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.
Yes, perception. I think the view of some French (in particular) people would be that a sexual outside affair is at worst only "the chips are down" and that the commitment is still there. They would say that Americans view sexlessness as remaining true and committed, while an outside sexual affair is breaking the commitment. Which was my point.
I've personally heard the opinion from a French woman that when she got married, she wouldn't be all that upset if her husband had a brief sexual fling on a business trip, for example, as long as he remained committed and loved her (his wife). I remember thinking, wow, that wouldn't be the prevailing opinion in America, that's for sure.