Cheese in the Trap..
↓ Oh yeah I also second She Was Pretty, forgot about that one
I second cheese in the trap.

my biggest one was she was pretty.

also, boys over flowers, even though I haven't finished that one yet
Midas - I just don't think they fit each other, even though they are great individually
Good Doctor.  No chemistry and the male lead had a child's mind socially.  Not believable that they would end up together.
REPLY 1988 - i still think there was late shuffling of writer Lee and shin PD, just to have that 'aha' moment of being shocking ending. Felt so cheated from this drama. Still breaks my heart thinking about the end of this drama. Though i did skip the last episode, too painful to watch. I could never ever ever ever accept that ending. 

The K2 - its more of the portrayal of Yoona that turned me off the Anna character. I feel like if they had cast another avtress like Park Boyoung, Moon Geunyoung
and etc, i think Anna would not be soooo bland and flat like a wall flower

Drinking Solo - not only was the guy such a jerk, the girl was such a doormat. I dont see a healthy relationship between this 2

Boys over Flower - this one is perception difference. I loved Meteor gardens take on how much the guy loved the girl. Than anything the BOF remake did pales in comparison. Thus i was sorely disappoointed they end up together

Big - its been such a debate who she actually ended up woth. But man that ending feels so confusing and frustrating. I would sonner wanted the girl alone than that ending

Hit the Top - i went  eww and urghh for that couple everytime i watch them

Heirs - they felt so immature to really be with each other. They totally didnt feel right with each other. But then again nothing in that drama felt right, except for Bona and chanyoung. 

yongpal - i didnt understand this couple together. They totally felt so wrong. Much like the k2 couple. 

heart to heart - its my choi kang hee allergy that constantly makes me biased to her being with the male lead

cinderella and 4 knights - i so loved jung il woo but i so wanted them to not get together. The female character became too irritating at the end
i second doctor stranger , who are you school 2015 , and i really hated the main leads getting together in who are you (2013) .. 
I second:
Goblin (they look like siblings or sth)
The heirs (abusive male lead)
High society (no chemistry, no reason)
and...
Hanazakari no kimitachie (she was blind :/, I didn't feel any real conexion between the main couple but instead had a serious case of second lead synd).
Agree with the uncomfortable age differences mentioned, like Goblin for example... not my cup of tea so I had to drop...

Again, I agree with:

The Heirs : Tan was too controlling/abusive/bossy towards her for me to be comfortable with it... and I guess (unpopular opinion) but Lee Min Ho just didn't do it for me in this drama.

The K2 : I stuck it out because Ji Chang Wook and Song Yoon Ah excelled in their roles, but the Je Ha/Anna romance never sold me one bit and felt very forced from the start (I mean... come on... that CPR scene, and for her supposedly having social phobia, she opened up to him about her past preeeeetty quickly from the get-go). Not to mention that Anna as a character just felt very... two-dimensional and flat, probably from a combination of the writing as well as Yoona's acting. I would've much preferred it to have been more of a guardian/familial and strictly platonic connection between those two, and in my opinion there was far more chemistry/potential for Je Ha/Yoo Jin lmao... the acting chemistry was on point and I loved seeing their interactions, though it's a shame about how those two ended up... It was disappointing, because I've liked the lead pairing from every other Ji Chang Wook drama I've seen, but this one was a big no-no.
I will only say dramas that were already mentioned but as soon as I saw the title of the topic, I thought about:

- She was pretty. 
- Who are you: School 2015
Cheese In Trap
Doctor Stranger
reply 1994
reply 1998
I remember you
Que Sera Sera.  
He's a violent piece of crap who shouldn't be with any woman (i dropped it half way through because of this)

Tomorrow with You
He's disrespectful and manipulative.  She deserves better

Warrior Baek Dong Soo,
The romance was so weak in this they should have left it out.

Circle
this is why i gave this drama 9.5 instead of 10.  the romance is unnecessary.

I Remember You/Hello Monster
Even though I love this drama, i think it would have been better without the romance.  It felt "token"

Second Love
Who falls in love because someone dances AT them?  This whole drama is nonsense.



Hana Kimi and Itazura na Kiss, the female leads should have chosen the 2nd male leads in both these dramas!!!

Oh My Ghostess.... I've never felt so betrayed from a drama series. I can't tell you who I prefer just in case you haven't seen it... But god, the ending couple I did not agree with.