When is, “Till Death Do Us Part” over before death? How do you know before it’s too late, that a relationship is beyond you to make it work again?

Zoe Briggs gives 10 signs to watch out for at http://www.cosmopolitan.com/uk/love-sex/relationships/g820/how-to-know-your-relationship-is-over/

…but what makes love grow cold, what turns friends into enemies and what makes believers in the all conquering power of love abandon their vow to love forever?