I once looked into becoming a marriage counselor for Relate!
(I failed when I was asked how I would deal with a guy who beat up his wife. I told them I would give him a good hiding so he would know how it felt.... WRONG!)
Anyway, part of the training was dealing with very contentious issues such as the one Teejay described. Basically, each person agrees that the contentious subject is put "on hold" for an agreed period of time, say 3 months. This gives both parties a chance to reflect. The subject is not mentioned at all. When one person feels that the other is breaking the "hold" and pushing the envelope he/she refuses to comment in return and simply gives the partner this signal:
This is a "I am immune" signal in the UK. After the agreed period of time, the subject can be brought again. Often, but by no means always, the heat has gone out of the original issue and sometimes a solution or compromise can be found. Some couples find that the peace that they have enjoyed during their "holiday" is too good to lose and settle for leaving things just as they are.
Englishman.