I don't think it's that disappointing, actually, since it revealed that they were childhood friends together, all 3 of them.  It makes Eun Hyuk's character make sense now.  I didn't want it to be Eun Hyuk originally, since his behavior wouldn't make any sense if he was the one who slept with Yoo Jung.  But now that I know his backstory, it works.  And we also see him ignore a call from Yoo Jung, so he's committed more to Ji Wook than his (former?) crush, so... I mean, that's pretty fascinating for a second male lead!
LOL, Panda, it's not that simple and we don't know the whole story yet.  And, yeah, of course there's no excuse for sleeping with your best friend's GF.  It's a GOOD thing that he doesn't try to make excuses.  

There's more story yet to be told here.
But who wants predictability? Being curious is what keeps me engaged and wanting more. 
I mean, we still haven't heard Yoo Jung's reasoning yet... yet Eun Hyuk couldn't stop himself because he liked her first but why did Yoo Jung cheat on him... that seems like it will be the bigger mystery then again who knows
disappointing.... i know iknow 'what do u expect from a kdrama??' but since its a new story they should have seen this same pattern from before and try to come up with something more fresh..... i was going to say ' cheating and regretting ' is cliched but 'cheating and not regretting' is also cliched.. why did they even make these character go thru all these at all? we could have a solid two main couple romance, imo. and let them solve crimes .... i still like bong hee and ji wookie a lot they have good chemistry
IDK, a childhood friendship broken up by sexual infidelity feels rather interesting for a kdrama.  To me.  But I've only got 42 shows in my Completed list.

And Eun Hyuk is amazing.  It's not often we see peacemaking so realistically portrayed.  Most kdrama characters run from their guilt because that's easier to write.
hi guys could anyone tell me how to get this drama its unavailable in my country. even a link please

ji wook, eun hyuk and yoo jung wore best friends (since childhood i think), at some time eun hyuk started liking yoo jung but she ended up dating ji wook. even though he liked the friendship he had with ji wook, he slept with yoo jung but ended up regretting doing that and that's when he have been trying so hard to have ji wook's confience back by acting so cute and caring with him always trying to make him laugh.... (it's just my opinion xD i'm currently watching this drama so i'll see if it's really it what happened)