The Diary of Teenage Dream (Sood Tae Jai Ja Kwai Kwa)

Pattana is the son of Pol, a humble orchardist. Pol has five children: Phutjeeb, Phannaphong, Pattana, Pinnarom, and Pornphut. Pol carries a deep-seated bitterness because he lacks a high education and has to toil in the orchards, unlike his younger brother, Potjana, a brilliant student who became a wealthy businessman.
Fixated on this insecurity, Pol pins all his hopes on his eldest son, Phong, who is academically gifted. This leads to blatant favoritism; Pol loves Phong the most and supports him unconditionally while being unfair to his other children. This indulgence turns Phong into a selfish and entitled person, though their mother, Boonsong, often tries to intervene when she sees the injustice.

The Struggling Middle Son

Pattana is not good at school but possesses a natural talent for mechanics and a kind heart. Since he was born during a massive flood that devastated the orchard, Pol blames him for being a "jinx." Pol despises Pattana’s choice to study auto mechanics, viewing it as a lowly profession, and eventually stops funding his education.
Fortunately, Kamnan Don recognizes Pattana’s potential and hires him to work in the orchard so he can put himself through school. Pattana is infatuated with Wanram, but she merely uses him for labor. When she is with Phong, she acts sweet and asks him to tutor her. Meanwhile, the youngest son, Pornphut, loves art, which Pol dismisses as useless.

Urban Lives and Heartbreak

Phong brings pride to his father by getting into a prestigious university in Bangkok—the same one Wanram attends. Wanram moves to the city to live with her Aunt Kaew, a modern, independent working woman whom Wanram admires as a role model.
Pattana is heartbroken when he realizes how close Wanram and Phong have become. Wansawang steps in to comfort him. Meanwhile, the eldest daughter, Phutjeeb, goes to hair-styling school and is nearly tricked into a hotel room by a male admirer, but she is rescued by Waitoon. Waitoon is impressed by Phutjeeb’s modesty.
As Phong and Wanram enjoy their freedom in Bangkok, they become reckless. Concerned, Aunt Kaew asks Pattana to help look after Wanram. To deceive her aunt, Wanram allows Pattana to pick her up and drop her off for a while. Meanwhile, Pinnarom qualifies as a nurse's assistant and moves to Bangkok.

Secrets and Struggles

Waitoon graduates and becomes a lawyer in Bangkok. He is shocked to discover that Phutjeeb is actually his cousin, and they must hide their previous acquaintance. Phong discovers this secret and uses it to blackmail Phutjeeb whenever she catches him doing something wrong.
Pattana’s mechanical work thrives, and he saves up to buy land for a garage, only to be swindled into buying "blind land" (land with no road access). Pol mocks him for the failure, but Wansawang remains his pillar of support. Eventually, Pattana lands a major contract, allowing him to open a large, successful garage. However, he becomes distracted, causing Wansawang to feel neglected and turn to Dr. Chun for comfort. Although the doctor loves her, she only sees him as a friend.

The Family Crisis

During his final year, Phong’s grades plummet and Pol falls ill. Pol longs to see Phong, but Phong makes excuses about exams. Only Pattana and Pinnarom come to care for their father. When Phong runs out of money, he returns to manipulate Pol. Although Boonsong refuses to give him money, Pattana helps him out—only for Phong to waste it on partying. When Pattana confronts him, Pol still takes Phong’s side.
Phong tries to take Wanram to a graduation party, but she refuses because she has started dating a wealthy socialite. Phong takes Pinnarom instead, where they meet Chao, a powerful businessman known for keeping young girls as mistresses. When Chao suffers a heart attack, Pinnarom uses her medical training to save him. Intrigued by her, Chao discovers her family's background and offers to buy their land at an inflated price. Kamnan Don senses something is wrong and warns Pol and Boonsong not to sell.

Betrayal and Redemption

Pattana’s garage continues to grow with Wansawang’s help as his accountant. However, Nidawan constantly tries to interfere. Phong, unable to hold down a job, blames his lack of a Master’s degree and wants to study abroad. Chao seizes this opportunity, offering to fund Phong’s studies and "help" the siblings if Phong brings Pinnarom to work as a private nurse for a "patient."
Phong traps his own sister, and Pinnarom is drugged and raped by Chao. The family is devastated. When Pattana finds out, he is furious, but Phong continues to play the victim. Pol blindly believes Phong acted out of good intentions. In a rage, Pattana cuts ties with his father.
Pol’s health worsens as he realizes his favoritism has torn the family apart. The doctor recommends a heart transplant. Pattana drops his pride and returns to his father’s side. Meanwhile, Phong only reappears when he hears Pol is dividing the inheritance. Pinnarom, traumatized, tries to attack Phong, but Pattana stops her. Pol finally admits his mistake: he gave Phong the best of everything, yet it was the children he gave the least to who achieved the most.

The Conclusion

Pinnarom decides to work abroad to escape Chao’s harassment, with Waitoon helping her sue Chao for damages to fund her journey. Pattana returns to his garage but feels a void; Wansawang is angry, believing he still loves Wanram, and Nidawan has lied about being pregnant with his child. When Wansawang brings Dr. Chun to visit, everyone assumes they are a couple. Panicked and finally realizing that Wansawang is the one he truly loves, Pattana rushes to confess his feelings before it's too late.