Please suggest the latest dramas that are the best and a must-watch. 

Also, I'm looking for a drama that has a love story of a popular boy/girl meets ordinary boy/girl. Like idol-fangirl relationship. Something like that. Please please suggest some and where to watch.

I'm also looking for a drama that the girl and boy seems like they'll end up with each other but they won't. Do you get me? Haha. Because they look so cute with each other and they're like a perfect couple but they're not destined for each other so they will never happen. Hahahaha do you guys get my point?? I hope you can suggest a drama.

THANK YOU!!

You're Beautiful and Ma Boy fit the girl meeting idol and romance requirements.
so.. basically you are looking for something like the heirs and stories with (heavy) second-lead syndrome? >_< (i am sorry if i misunderstood your request :'D)

in that case i recommend Boys over Flowers (kr)/ Hana Yori Dango (jp) - i realize it is not the latest drama but it is a classics of this genre. i think japanese version is better and timeless. fun fact: main actors are (were?) actually dating each other :))
I second You are beautiful because meets all your requirements and I also really enjoyed this one.
I noticed you have in your ptw list Flower boy ramyun shop and Flower boy next door. Both of these are somewhat about (average) girl meeting idol-like cool guy and with strong second male lead character.
Hana Kimi (jp)/ To the beautiful you (kr) - girl sneaks to all-boys school to meet her idol and to help him overcome his injury. japanese version is more comedy oriented (it is really hilarious), korean version is more... korean.

as for the "latest dramas that are the best and a must-watch" (because i guess these dont have to contain aformentioned story trope)
School 2015: Who are you - this years drama which was pretty good in terms of story and acting. has some mystery elements and good love triangle
Reply 1997 - my all time favourite 
Healer, Kill me Heal me, I hear your voice - these were dramas that were generaly adored and highly rated (i have not seen them so i am just mentioning them)
a drama that the girl and boy seems like they'll end up with each other but they won't:

Doctor Stranger - the 2 main leads have so much chemistry but the writer really trolls you until the last episode to tell you who he ends up with.... I really didn't like the ending tbh
*All of these are Korean dramas*

Dramas that the girl and boy seems like they'll end up with each other but they won't: Endless love, What happened in Bali, Beethoven virus, Cruel City

Must watch latest dramas: Falling for Innocence, Oh my Ghost, Kill me Heal me

Popular boy/girl meets ordinary boy/girl: You're Beautiful, Boys Over Flowers, Tomorrow's Cantabile, Que Sera Sera, Goong
How about a drama where the girl falls for the second lead instead of the first?
If you are brave enough, you could try Diamond Lover (Chinese drama) which stars Rain as the main lead *Spoilers in white* (he didn't get the girl - she ended up with the 2nd lead instead)