I think that a lot of LD spouses justify their rejection to soothe their own guilt. I think that on honeymoons, anniversary trips, and the like, they know what the expectations are and can find little justification for not getting it on.
I know for my LD spouse, "getting away from it all" seems to help. Unfortunately, it is impossible to replicate that in every day life. I have tried unplugging the telephone, drawing the blinds, and pretending we are at a hotel, but real life always intercedes. I guess more trips are in order.