I don't really think that he is fickle, more like he's strong willed and decisive but also a little reserved and shy, I mean who wouldn't be tempted by the person you loved for three whole friggin years saying their sorry and wanting to get back together, he even admitted that he still has a lingering attachment but he knew what was good for him and handled that situation perfectly without wavering and giving in when most people would. (▰˘◡˘▰)
Also frick that guy for even putting him in that position, I swear if he shows up again I'm gonna invente a way to bitch slap fictional characters just for him
( ̄ε(# ̄)Σ (︶︿︶)=凸

Feeling a bit giddy with the other guy's confession but then coldly rejects him, and then cries over it later, and finally becomes upset over ahjussi. Dang our boy's fickle. At least he admits it. Hope he won't be seduced by that HW in the future.