Ok, so why not allow these friends to form some sort of civil union? Give them legal means to take care of each other and equally a simple legal parting of the ways if necessary. This could change a lot for people who will never marry. And, guess what? Think of the enormoous and potential impacts it would have on the economy. In fact, it would spur a whole new industry of celebrations, legal, accounting...etc. Capitalism at its finest with human benefits.