@mandy: MGY did not become Sukkie's bestfriend overnight, they're really best friends.
But it's just like that, Sukkie even denied being linked to MGY before they have brother-sister
relationship. I think the interviewer knows already that Sukkie and Shin Hye are "Yeonin"
that's why she said girlfriend, and his laughter confirmed it, the good one answer means correct
or you're right Sukkie did not just say it directly.