Why LOVE marriages fail?

Basically I feel every marriage has its own up-s and down-s. But main cause for failure of love marriages is starting with high level of expectations. When expectation is sky-high then even a small lapse seems like a huge let-down. Maybe because the partners are so sure of being happy together, that they can't accept a little bit of disappointment.
But arranged marriages start with partners being not-so-sure..not so-high expectations from either end..so a small gesture seems like a big step forward..partners are more ready to take that extra mile..

Purely my own views on observing close friends and relatives...exceptions always may occur.

 

Is there really a reliable survey done on love marriage vs arranged marriage failures? Or are we just assuming based on people we know.