The vow to reincarnate came from a series of fantasy novels," Douluo Continent," and its derivative works, written by the Chinese online writer Tang Sanshao. The content was: " I am willing." "I'm willing." "If there is a next life, we will never meet again."
"Douluo Continent" told the story of how Tang San, who had transmigrated to the Douluo Continent, cultivated his spirit step by step, becoming a god from a human, and finally eradicated the evil forces on the Douluo Continent, avenging his mother's death, becoming the Douluo Continent's strongest person. In the novel, reincarnation was a special form of love. In this form of love, if one of the lovers died, the other party could use his soul as the price to revive the dead person in another form, but the revived person would lose the memories of the previous life.
While waiting for the TV series, you can also click on the link below to read the original work of " Little Fox Demon Matchmaker " to understand the plot in advance!
Since we don't have much information about this 'irena's vow real story', it could be a story where Irena vowed to protect something or someone. It could be her family during a difficult time, or perhaps she vowed to uphold a certain value in a community that was facing challenges. There are so many possibilities depending on the background and details of the story.