Ballad Prince Cho Kyuhyun's fan

In 1988, the late Israel Kamakawiwo'ole called a sound studio at 3am, said he had an idea, and asked if he could come record. He was so polite, the studio owner said yes even though it was late. He showed up 15 minutes later, sang and played his ukulele, and recorded ‘Somewhere Over the Rainbow’ in just one take. It is now the most requested version of the song by far. Source Source 2

Idols are meant to be pretty, fun, cute, and flirtatious, so that fans can fantasize about being with them which drives sales of branded merchandize.

An Idol that has romantic or sexual pursuits is no longer perceived as available, in addition to it conflicting with fetishized virginity.

Basically, the Idol industry in Japan is the epitomy of a misogynistic sex-sells industry where the product is a fantasy relationship with a woman who is performing to make herself desirable. 

Many, many idols are extremely salty about this and will go to great lengths to mock and disparage the system, but they can’t do much to get it changed or go against it because their entire career will be destroyed if it is publicly discovered that they have or have had anything close to a relationship or sex.

And the companies absolutely do fire idols who do so, and destroy any potential they have as a career public figure for the rest of their lives. It’s horrifying.