It's about how everything changes every time they're both around? No matter how they keep it secret, the feeling's just bursting that it's so obvious. No way hiding but they still want to call it secret (everyone knows though). Gosh, I came across this yt video titled "eunhae is obvious! " with this song in the background. I guess the lyrics fit well what's on the video that it's just self-explanatory. Watch it: http://www.Youtube. Com/watch? V=u6xmxkyhuxo.
Note: both guys have had relationships with fine girls and they're definitely not gays. Fans like to ship them because the group has this super friendship that you just want them to end up together. Eunhae is just one couple from the group.