Well congratulations to Joe and Marjorie from me as well. I hope things work out well for them and that they have many years of happiness together.
As regards the success and failure of marriages in general, can I just put in my tuppence worth and comment that it is sometimes the most unlikely marriages that survive, and those that seem rock solid that suddenly go into decline. I suppose if someone knew what that 'secret ingredient' that makes them work was s/he would be a millionaire. In fairness I imagine the vast majority of people who marry genuinely do intend it to be for life. Unfortunately for some it just doesn't happen like that.