I don't think we were discussing "religiously motivated" marriages but rather that a shared religion (presumably one that both participants had before the marriage) was an additional social pressure "like" arranged marriages.

In any case, I think that social pressure can be a pretty strong force and that it tends to counteract the sort of selfishness that leads to a "bad marriage". Of course bad marriages will statistically happen but I don't think you can claim the huge number of divorces we're seeing are all "bad marriages" - my premise is that many could be cured if both participants cared to work a bit.