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.'
The Bible is the only credible guide either as to the real relationship between man and the earth and the great Creator of both or concerning the purpose of the creation of both.