I like this a lot. I think for a lot of BS', we tend to be a bit more 'established' when it comes to boundaries, etc., especially those BS' who have never cheated in their lives (I'm one of them). And after reading your post, I completely agree. I've never thought to say "I can't cheat", as it just sounds incredibly weird rolling off my tongue, and makes me think that I am being stopped from cheating my an external force, if you will.
It's like saying to a friend, "I can't go out with you tonight." That would imply that you WANT to go out with that friend, but for whatever reason(s), you simply cannot. Make sense?
For me, I firmly believe that "I DON'T CHEAT". It's just written in who I am. I've made certain promises and boundaries with myself that I must honor (note: my reasons for "I DON'T CHEAT" have NOTHING to do with my spouse. It is ALL within me!). By saying that I *DON'T* cheat, I am saying that my internal desire, force, etc,. is dictating that cheating is simply just something I will not succumb to. But again, it's 100% due to my own principles and boundaries, really not related in any way to 'loving' my spouse, etc. May sound counter-intuitive, but that's the truth. Obviously, 'loving' your spouse doesn't stop people from cheating anyway, so really, I think it is within each of us to honor ourselves, out commitments, etc., and we do so by saying DON'T instead of CAN'T..!
Thanks again for sharing this.