"Sometimes you just have to turn around, give little smile, throw the match, and burn that bridge." I've adopted this a long time ago and it changes you for the better. Those bridges were going to crumble any way, might as well give them a hand.
Not at all true -- there is the third, less conventional option of simply being with that person, in love, for the rest of your lives without the bindings of marriage. Then you know you'll stay together not because it's difficult to get out of the relationship but because you truly want to be together. It is a mark of a much stronger commitment to NOT marry.