Consider and act with reference to the true ends of existence. This world is but the vestibule of an immortal life. Every action of our lives touches on some chord that will vibrate in eternity.
I honestly believe you can never tell if a relationship is going to last. In my own marriage, which is going on 14 years, I don't think of it as 'I'm going to be with this person forever.' Instead, I think of more like, 'I'll probably be with this person for the next six weeks. Then I'll re-evaluate.'
God has lent us the earth for our life; it is a great entail. It belongs as much to those who are to come after us, and whose names are already written in the book of creation, as to us; and we have no right, by anything that we do or neglect, to involve them in unnecessary penalties, or deprive them of benefits which it was in our power to bequeath.