There are so many reasons behind the destruction of love. 1. Character: the character of the both partner matter a lot. Sometimes the aroma of food doesn't determine the taste. At the beginning you felt it's nice and great food but wait until you taste it then you can judge. 2. Money: Money can make the love sweet at the first sight. With money love can be deceived and once the desire is achieved it fade away. 3. Inpatient: When the both side are not patience enough to study each other.
Spirit of heart: When you failed to understand the matter of heart, when the heart doesn't love and forcefully entice by main appearance, when the beauty deceived the heart and override the heart the love won't last.
In conclusion: Learn to love without gift, learn to love without appearance, learn to love without enticement, learn to love without money, learn to love without position, power and influence, learn to love without deceit, learn to love with your heart and you will never wish to live without the one your heart choose to love.