thanks for the summary.The title is "Khun Chang and Khun Phan" which just means "Sir Chang and Sir Phan"
Kwan Usamanee was in this lakorn too when she was a little girl and also Tom from "room39" is in here when he was a boy.
Here's the summary from wiki:
Khun Chang, Phlai Kaeo (who later is given the title, Khun Phaen), and Nang Phim Philalai (who later changes her name to Wanthong) are childhood friends in Suphanburi. Khun Phaen is handsome and intelligent, but poor because the king has executed his father and seized their property. He enters the monkhood as a novice to get educated, excelling at military skills and love magic. Khun Chang is ugly and stupid, but rich and well-connected at the Ayutthaya court.
By age 15, Phim is the belle of Suphanburi. She meets Phlai Kaeo when putting food in his almsbowl at Songkran (Thai New Year). Sparks fly. They have a passionate affair, with him shuttling between the wat (Buddhist monastery) and her bedroom.
Khun Chang is also smitten by Phim. He competes for her using his wealth and status. He offers to give her mother Phim's weight in gold. After Phlai Kaeo and Phim are married, Khun Chang maneuvers the king to send Phlai Kaeo on military service, and then claims he is dead. When Phlai Kaeo returns victorious, Khun Chang plots to have him banished from Ayutthaya for negligence on government service.
Phim (now Wanthong) resists Khun Chang. But when Phlai Kaeo (now Khun Phaen) returns from war with another wife, they have a jealous quarrel. Wanthong goes to live with Khun Chang, enjoying his devotion and the comforts afforded by his wealth.
When Khun Phaen's second wife, Laothong, is taken into the palace by the king, Khun Phaen regrets abandoning Wanthong. He breaks into Khun Chang's house at the dead of night and takes Wanthong away. At first she is reluctant to leave her comfortable existence, but the passion rekindles, and they flee to an idyllic but frugal sojourn in the forest.
Khun Chang tells the king that Khun Phaen is mounting a rebellion. The king sends an army which Khun Phaen defeats, killing two of its officers. A warrant is issued for his arrest. When Wanthong becomes pregnant, Khun Phaen decides to leave the forest and give himself up. At the trial, the charges of rebellion are disproved, and Khun Chang is heavily fined.
Khun Phaen angers the king by asking for the release of Laothong. He is jailed, and festers in prison for around twelve years. Khun Chang abducts Wanthong and they again live together in Suphanburi.
Wanthong gives birth to Phlai Ngam, her son with Khun Phaen. When Phlai Ngam is eight, Khun Chang tries to kill him. Phlai Ngam escapes to live in Kanchanaburi with his grandmother who teaches him from Khun Phaen's library.
When the kings of Ayutthaya and Chiang Mai quarrel over a beautiful daughter of the King of Vientiane, Phlai Ngam volunteers to lead an army to Chiang Mai, and successfully petitions for Khun Phaen's release. They capture the King of Chiang Mai, and return with the Vientiane princess and a great haul of booty. Khun Phaen now gains status as the governor of Kanchanaburi. Phlai Ngam is appointed Phra Wai, an officer in the royal pages.
Khun Chang gets drunk at Phra Wai's wedding, and the old rivalry returns. Phra Wai abducts Wanthong from Khun Chang's house, prompting Khun Chang to petition the king for redress. At the subsequent trial, the king demands that Wanthong decide between Khun Chang and Khun Phaen. She cannot, and is dumb-struck. The king orders her execution. Phra Wai pleads successfully with the king for a reprieve, but the order arrives fractionally too late to avoid her execution.