most of the love marrage is failer why?

The one word answer is "Expectation". Any relationship depends on expectation. in case of love marriege, both the partners have lots of expectation each others. before marriege they wont see any bad behaviour or bad qualities or hear any bad words from partner. they are like two perfect partners. so when they jump into marriege they expect such a partner life long. to err is human . so the problems come out. But incase of arranged marriege, both partners dont know much and they starts to understand each other only after marriege. so they will try to adjust