After reading through everyone's detailed analysis, here's my take on the whole situation:
1. Personally I have never seen Sukkie like GLOWING with happiness whenever his around Shin Hye. No joke. I think you'll only see that kinda 'sparks' between couples or potential couples. At the end of the day, mere FRIENDS don't act like tat to each other!!!
2. Somehow, I really thing their whole break thing was because Shin Hye really fell for Sukkie. He said 'she needed to adjust back to herself rather than MN'. Well MN was in love with TK, hence the obvious fact is that SH fell in love with Sukkie. MOST IMPORTANTLY, sukkie KNOWS tat!!!! (though I have no idea how sukkie feels lol! - I think at the time he doesn't realise that he fell in love with SH too.)
I guess they aren't shy around each other and is very open about it (to each other) so maybe they probably decided it's the best to take a 'break' from each other to see if it's just their characters feeling towards each other or the real deal.
3. I think after the whole ordeal, they both realises that they r in 'love' with each other. Or at least have this certain attraction with each other =]. I think sukkie probably realises that no one else can make him as happy as SH. While SH is probably unsure about taking the next step with sukkie because they r both young n other factors that will come into play in their lives - eg antis n stuff.
CONCLUSION: I think the 24hrs theory is correct, they r probably keeping an 'under-cyber' thing with each other atm. LOL!
Only time will tell~~
PS - I kinda hope they won't come out n declare their relationship.. coz once they declare it... things will always go sour =[