Which drama's to avoid?

Hii everyone! I finished watching Romance is a Bonus Book and i didn't like it at all. It wasn't the age difference that bothered me. Drama's like I can hear your Voice and Witch's Romance made the age difference work out pretty well. What bothered me was that the main heroine built up a wonderfuk life, got a job, got a partner and out of a sudden she broke up with him (the second male lead) to get into a relationship with the first main lead... like what.. why.. it was so so perfect between these two. It was super cute yet she broke up with him JUST BECAUSE it's the first main lead.. 

My question is if there are other dramas that are like that.. ? I'd like to avoid them. Other example that did the same thing and that i absolutely didnt like are:

•The Heirs

•Cinderella and four knights

It's not just a second lead syndrom.. it made the whole story shitty (it my point of view at least lol i'm not saying that if you liked these dramas that you have a bad taste. I'm saying that it's just not my cup of tea! <3)

Ooh and another drama that i didn't like at all is "Man to Man". Park Haejin is my favorite Actor, and he did an amazing job! It's the woman who bothered me. I hated this drama so so much because of her. NOT the actress, i'm talking about the role she was playing. 

Thanks to everyone who comments and gives me a reviw / recommendation / tells me what better to avoid <33

• I also dont like Romance is a Bonus book. but just to clarify, the husband went bankrupt and then he cheated on the FL. And hubby was the one who started the divorce proceedings because the othee woman was pregnant. But that background plot is not a factor in not liking the drama, the writing was just wrong in this drama
• I agree on all dramas you've mentioned (heirs, C&4K, M2M), and main reason is lack of chemistry. Secondary is probably due to weird narrartive.
• For dramas which i wanna suggest you avoid  mainly for reasons ive mentioned above, but mainly lacking of chemistry. Here are some:
  • Entertainer
  • Black Knight
  • Bride of Haebaek
  • Born Again
  • Backstreet Rookie
  • The Liar and His Lover
  • Revolutionary Love
  • Lucky romance
  • The Time We Were Not in Love
  • Sweet munchies
  • Hyde, Jekyll, Me
  • King: eternal monarch
  • Record of youth
  • Was it love

1. To all the guys who loved me -- trash, just trash. I like the actors but the plot is nonsense and you can't feel the chemistry, the romance is sooo cringe 
2. Reply 1994 -- some could like it but not if you have 2nd lead syndrome... plus it was dragging, the last 7-8 episodes could have been avoided