I finished this very uncomfortable to watch dorama. The FL is so unlikable, she seems a absolutely empty person: no personality, no backbone, no friends, no talents, no brains, no common sense. She thinks she can't live without a man.
The dorama makes a social commentary on the social pressure on women to marry and have children, about this mentality that a woman is incomplete without a husband and children. This may be part of what made the protagonist so pathetic but in anyway justify her actions.
She is a completely fucked up person and this is clearly shown already in the beginning when she smells that boy's neck. Only a fucked up mind would remotely consider she would have any future in a "relationship" with a 15 old boy.
I completely disagree with people here saying the dorama makes apology to an adult making sex with a minor. It's said several times that she was committing a crime and more important: it's shown how screwed was all that situation. The boy obviously wasn't mentally mature to take the situation and we see how broken he became.
The scene where she goes to his school and sees him playing with his friends is so uncomfortable, it's so absurd she thought she would have a place there... again, completely fucked up.
At the same time I don't see the dorama making apology to the FL actions that happy end didn't seem right at all, because that fucked up woman fucked up that boy's life and mind and in the end everything was ok and I was like "wtf, I can't believe it will end this way". It ended that way.
One last reminder: this is not a romance, it is a story about a fucked up woman who screwed a boy's life because of lust. If you are overly sensitive don't watch.