irmar

Well, we know from her inner monologues that she definitely doesn't feel the same. She saw him as a cardboard character when they were out eating.
About the "reading her like a book". When you are in love, such things change, because insecurities kick in.

Beautiful comment, and especially since it seems to come from a younger person. I am happy to find someone so mature and compassionate in the comments. I wish you all the best with your relationships, now and in the future.

I think I saw a "12" mark at the beginning, meaning it's suitable for 12-year olds. That would explain it. Although, kisses apart, the 12-year olds wouldn't understand the angsty dialogue and would find it boring anyway.

At the start she is 27 and he is 19 so it's 8 years. No big deal.

https://www.viki.com/tv/38667c-dear-x-who-doesnt-love-me and
https://kissasian.li/Drama/Dear-X-Who-Doesn-t-Love-Me

I wish I could demonstrate with a picture or two. You would understand immediately. But it's not possible here.

The way she reacted, she proved him right.

And it did.

I am talking about how she asked him whether he was swayed. That one he answered immediately with the truth, without hesitation, because he believed in their relationship being solid (wrongly). Don't you remember how the cells were debating, and then there was this writing under the question, saying it's a question with a time limit of 0.1 second? While the cells were debating, he had already answered.

She is insecure, immature and over-impulsive, she always tries to hide her true feelings and lives for the image she projects on other people.
One example is how she handled Woong.
Remember her lies at the resort, because she was ashamed of reserving the room with the clear-walled bathroom? She made such a fool of herself, and then was ready to go home ruining the whole vacation.
Remember her lies at that wedding? That she's supposedly going to have a wedding with Woong in Hawaii next spring?
And how she was ashamed of his style and dreaded how he would look in front of her friends?
Of course Woong was at fault for putting his pride first, no doubt about that, and that was the main reason for their breakup. But did she talk to him, did she fight for their relationship? She basically said "Oh, yes, that's a good idea, I was also thinking that" (not word by word, just the sense), to protect her own pride and not to seem like a loser.
One would think that after all that she would have evolved and matured. But this season proves the opposite.
She left her job on impulse, without thinking that a writer doesn't start making money until quite a long time, and her savings would probably not be enough.
The moment a contract is announced (not even signed! And anything can happen, remember the job offer to go back to Daehan noodles, that was taken back without warning?) she invites her friends and treats them to dinner in an expensive restaurant, spending almost all her remaining money.
Not only that, but that was the long-awaited reunion with her boyfriend after a long time (we aren't told how long). It was to be a romantic getaway, but she invites two other people. What???
A more recent example, the cake scene. A confident person would have laughed and said to Control Z: "Hey, you were right, this ginger pie sucks. Let me order something else". And they would both have laughed it off. Instead she had to gulp it down and do all this theatre, which of course didn't convince anybody, just because she didn't want to "lose face". Like a 12-year old.
When, in Jeju, she has the discussion with the young woman, she immediately takes her bags and leaves, without answering her phone, making him search here and there on the island. She doesn't even bother having a conversation with her boyfriend, to give him a chance to tell his side of things. Doesn't he deserve as much, after one year of his having shown a really good character, supportive and warm towards her? AAAAND... She had bragged to Control Z about how honest her relationship is, but then when her boyfriend is completely honest (anybody else would have told a small lie on being swayed) she rewards him ... by dumping him.
And you're asking what's annoying about her? She still has a lot to go towards maturity, if it ever comes within the next four episodes.

But we saw her in a picture, getting married - although the groom's face wasn't shown, it was definitely a wedding picture.

The part about being swayed or not was the defining part, not the why he moved house. That part he could well have concealed. He replied quickly with the truth.

Frankly for most of the series I've been annoyed at Yumi more than anyone else.

She does make wild decisions. Such as leaving her job before having anything sure in her hands. Such as leaving her boyfriend based on something someone else said, without even talking to him first or giving him the opportunity to explain himself. I mean, after a year of relationship, didn't he at least deserve that much?
I'm saying that Yumi acts on impulse, and it's not the first time either.

So he was penalized for being honest.

Is she that perfect that she needs a perfect man? Who is perfect in this world?

Can you imagine Yumi's reaction if Babi told her about the confession? No, just imagine. And them being thousands of miles apart.

Very well said, my feelings exactly.

Yes, some people just don't want to make the effort for a relationship. Quitting cowardly is much easier. It does hurt, but it's easier.

See, when he did tell the real truth, honestly, he was punished for it. Because Yumi doesn't have the maturity to handle it.