LW, yes I have struggled with ever filing for D. When I spoke to a lawyer about 6 weeks in to our sitch, I almost felt dirty afterward. (Of course, that could just have been due to talking to a lawyer! I kid I kid!)
The 1 year thing was on the advice of another anti-divorce author (not MWD). She preaches even tougher love than MWD for a WW. And her goal is that you do not allow limbo to linger for years. She recommends a one year deadline with the theory being that the WW really doesn't want to give up the cozy, secure life they have with their H, but just wants to run wild for a while.
I do not think I will ever have to file. I have stated on this forum before that due to my beliefs, the only time D is justified is due to physical infidelity. When it is not physical, but just emotional and visual (photos and videos) the line gets a lot more blurry. Yes I know that Christ said that looking on someone and lusting is committing adultery in your heart, but adultery of the heart isn't given as grounds for divorce. Sexual sin (called fornication in the King James) is.
So yes, very good question. Of course, D is a legal proceeding, not a spiritual one, so the real problem with D for anything other than adultery, is remarrying since you haven't been "loosed" from your MR by God.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018