It just means he is simping over her beauty or maybe has crush on her, we all simp over beautiful girls, hyunjin can't be blamed. 
fans used to ship him with yeji but its ok its his choice, he knows aespa girls are on the next level owiooowi 
other male idols also must be simping over other female idols too, its just that they don't keep their crushes as wallpaper. 
