Way before G.NA debuted, talks about Eunhyuk’s past girlfriends were being discussed on Korean fanblogs. This specific Sasaeng blog (Sasaeng means a fan who follows their idol 24/7) was created in 2007, more than three years ago.
The couples’ encounters were known to many of the Korean fans, but weren’t taken seriously, as she wasn’t even famous then. They broke up a long time ago, and the relationship didn’t last long. Choi Jina was also known to have been living in the States (and speaks perfect English) but also went back and forth often from the two countries to pursue being a trainee. Korean fans of Super Junior kept this piece of information to themselves, and didn't spread this rumor (resulting in the little information from Baidu, SJ-Market and other E.L.F. fansites). But now, she finally made a name for herself as G.NA, a solo singer debuting this past year.