First, “Some.” One of the interesting things about k-pop idols' date is that some of the idols who were reported to be enjoying date even didn't actually fall in love. Sounds weird? Well, here's the situation. Two idol stars are just in the beginning stage of love, and it's hard to say they're lovers. Koreans call such a relationship "some," just like the title of a famous song. In this situation, what are they supposed to do if media outlets report they're dating? They have no choice but to admit it, but some of them can't become real lovers after then.
Second, instant love. Not all the k-pop idols, but some of them have too many opposite sexes in their lives. They enjoy instant love and never have serious relationships. There is even an idol star who has dated more than two members of same idol group. Imagine a situation that an idol is somebody's ex-girlfriend, while she is another idol's lover now and her boyfriend's ex-girlfriend is the female idol's team mate. It's funny to see all of them singing together on the stage.
Third, pressure. Imagine all the people in the world know about your love life. Can you stand the pressure? Idols are people too. In addition, they have to meet their lovers very secretly for the simple reason that they're famous. Some of the k-pop idols who are reported to be enjoying date someone can't stand the pressure and say goodbye to their lovers eventually.
Fourth, hectic schedule. As you may know, k-pop idols are very busy. They have to manage a series of tight schedules at home and abroad, which means they do not have enough time to enjoy date with their lovers. You know the expression, "Out of sight, out of mind." Many of k-pop idol couples have broken up due to their hectic schedules.