After I Was Sent Off to Form a Marriage Alliance, My Brother Regretted It

The Female Lead Is a Princess. Her Childhood Sweetheart Betrays Her for the Second Female Lead, So She Goes to Marry into Another Kingdom

Looking for an ancient-era story. The heroine is a princess who was doted on by her parents and older sister to the point of death. Her childhood sweetheart marries the female rival to repay her father for saving his life, betraying the heroine. The heroine goes to marry the Prince of Beijun. I'm mainly looking for a story where she finds happiness through this political marriage.