Jian Qing Fen, just like all other career women, her life is a bit busy and tiring. Fortunately, she has a nice husband, and a lovely son. But for that reason, she's been leading a smooth-sailing and ordinary life, day after day. There's even nothing to complain about (apart from her mother-in-law and oh, her sister-in-law.) Because there's no suffering on her path to happiness, it's hard to say, "I'm so happy!" That's why she's been a bit annoyed lately and she's looking to stir up some trouble.

Everyone says that Rebecca is very pretty and capable, and that's why she's still single. Her abilities make men feel inferior to her. She enjoys her single life to a tee, but of course, there are situations that make her feel "alone." Her assistant chooses boyfriend over her when work gets busy, so she has to eat alone; her horny landlord makes up excuses to see her; and then there's that overwhelming sense of loneliness. She's not afraid of being alone, but when loneliness strikes, she can't help but think of that person that she mustn't think about anymore.

He Rui Zhi is a good man, or so everyone says. They call him a good son, a good colleague, a good supervisor, a good husband, and a good father. But to be good in every way, he has to make lots of compromises and betray himself. So, only he knows that there was just that one time when he nearly did what he truly wanted. But now, a shocking secret becomes his wakeup call. It turns out that everything he tries to protect may not be worth it.

Qing Fen often recalls how she suffered while trying to win over He Rui Zhi. So, when she finally married him, it's as if she'd won a medal. From time to time, she can't help but remind him of it. Not just him, but also her. Since Qing Fen liked Rebecca's SNS post, there's been no update. Qing Fen feels quite smug about it. Rebecca has to go through the pains of moving to a new place again, and it makes her remember the guy who once told her, "Don't be afraid, I'm right here." But now, all she's got left is a boy who would have dinner with her, the boy who has witnessed her fragility.

After Qing Fen's mother-in-law had a bad fall, her life changes drastically. She acts as if she's done something wrong and pays special attention to He Rui Zhi's mood. But the more careful she is, the more mistakes she makes. Yet looking at a worn-out and guilt-ridden He Rui Zhi, the emotional abuse seems to reveal the anger that she's buried deep down in her heart for 12 years. At the same time, Rebecca is trying to make up with her past self from 12 years ago. She lets go of her past and decides to move on to a new future. However, a competitive Qing Fen makes a decision.

As if she's woken from a dream, Qing Fen has gained enlightenment after messing up her life. If she and Rebecca are two entangling particles, then she would want Rebecca to live well. She goes around asking after Rebecca. Finally, she hears about their romance from Yu Xiang Li. Qing Fen is caught up in their love story, unsure if she's happy for Rebecca, or for herself. So, she decides to look for an answer.

What on earth is she doing here? Rebecca keeps observing Qing Fen, speculating about her intentions. Anyway, she's got nothing to lose now. So, Rebecca accepts her enemy's challenge. After they start talking, they talk about so much more. Then they realize that the enemy is the one who knows them best. It turns out that the one who knows me best hits me on the sore spot. In fact, there's only a fine line between a friend and an enemy. What actually trips us isn't the blooming flower on the other side, but ourselves.