edit: I read some of the spoilers from ep10 and my 1st prediction after ep1 was right, so that means the story was built on 1 plot move and 1000 misunderstandings and miscommunication ;D ie a waste of time ;)

the fl stands up for herself and she even called Dae Oh as a loser so they acknowledge his annoying side, but the wrist grabs drive me crazy especially the double wrist grab at the end ;/

they are not bickering, they are purposely hitting below the belt?. they might now be doing it becasue both are hurt and once the misunderstanding goes away they'll be all lovey dovey, but at the end of the day they chose to say/think those words....

my theory (not a spoiler) is that Dae Oh is the dad, self centered actor liked her too so he never cleared their misunderstandings if not add more fuel to the fire. she saw Dae Oh with another woman and she went to self centered actor ie the rain scene, and teacher dude loved her so much that he wanted to "take responsibility" for her and his mom hated that he was going to raise another man's kid so she bribed/hurt ae jung and told her to leave. I don't know how gangster dude is related, but add the actress and we'll get 10 more eps of misunderstandings and venomous fights ;/

it really can't be any other guy because 1- she was happy to see actor guy, 2- she didn't remember teacher dude 3- she didn't even know gangster guy. and 4- she hated seeing dae oh again. and the grandma did say "he's dead to her" so I mean you won't not remember the person you hate/love