The world is a collection of amazing amount of data but with no meaning to them. The human mind, aroused by an insistence for meaning, seeks and finds nothing but contradiction and nonsense. The more one puts himself to wisdom the more sorrows he attains too. Sorrows are the unasked compliments that come along with true wisdom.
Love has reasons too or to be precise it has attractions, attraction by beauty, attraction by intelligence, attraction due to the way we feel comfortable with them, attraction to the standard of living they could offer us and so on. Once the reason is lost, then it is a choice for us to decide whether to stay in a relationship or leave.