In 2015, Lee Seung Gi and Yoona have broken up after dating for a year and 9 months. I think many kpop fans felt sad about it because the two seemed to be a perfect match. Both Lee Seung Gi and Yoona are well known for their good nature and they're alike in personality, while they'd tried hard to protect each other. The official reason for their breakup was their hectic schedules.
However, there was another reason why they should break up. As you may know, for Korean men, the military service is mandatory, while Lee Seung Gi also joined the army in February 2016. I've served in the military too and saw so many soldiers who broke up with their girlfriends in the army. From my own personal experience, more than 70% of soldiers break up with their girlfriends after joining the army. As all the Korean young people know about this, some of them part with their girlfriends just before enlistment even though they’re still in love with girlfriends. They think it is a way of showing their consideration for their girlfriends because it’s true many girls who sent their boyfriends off to the army suffer from loneliness, while most of the couples split up eventually.
And do you think it was just a coincidence that Lee Seung Gi and Yoona broke up just days before Girls' Generation’s comeback? Ever since it was known that majority of the Girls' Generation members were dating somebody, some had had a dig at Girls’ Generation, saying it’s not Girls’ Generation but “Dating Generation.” At the time, Girls' Generation was at a crucial moment of its career. The girl group had to prove that it is a still No.1 girl group through its comeback because so many other popular girl groups such as SISTAR, AOA, Apink, and Wonder Girls made a comeback around same time, aiming at the No.1 position. And truthfully, Yoona's romantic relationship with Seung Gi was not helpful to Girls’ Generation’s career at all. It's sad that the good-looking couple has broken up, but the breakup was of help to Girls' Generation in a sense, ironically.