What he did before to that Jardim??

He befriended Jaerim and later SA’ed him because that shitty girlfriend (who likes Yuri) demanded him to do so, as to break off Jaerim & Yuri (jaerim’s bf) relationship. Jaerim really thought of Ayeon as a best friend on whom he can rely on, only to realise it was all a planned skit to separate Jaerim from Yuri.