"I love you darling, will you spend the next 12 years with me to raise a child together?".
This is not purely cynical... I think its so cool when two people who have been married for 15 years decide to celebrate with second marriage ceremony to launch them into the next 15.
The time commitment should set the financial arrangements when you divorce - Ending a life long marriage might split 50/50 whereas ending a 10yr marriage might confer a 15% mix of wealth shared.