“Indeed, sustaining a long-term relationship takes effort. 'You start to gain such familiarity that you don't put the effort into paying attention to each other,' says Sheryl Kingsberg, clinical psychologist and professor in the department of reproductive biology at Case Western Reserve University in Cleveland, Ohio. 'The long-term couple that's the most successful is the couple that has figured out you really have to work at maintaining a relationship and maintaining romance.'”