This movie is titled YOU AGAIN because it shows the story of people who met again after their terrible life in high school. The girl who was a nerd way back her high school life was going to be the sister-in-law of the cheerleader who used to bully her. She made everything to ruin her life and to make the marriage unsuccessful. Yes, she was successful but in the end she regretted and ended up accepting everything.
Her parents and her future sister-in-law's aunt used to be rivals in high school and her mom was always winner and the aunt was always forgiving. Funny, also their grandparents were classmates in high school and when they finally met on the wedding day of their grandchildren, they quarreled remembering on the times when they took rivalry over a guy.
The lesson to be taken part from this movie is that, whatever you do today always matter in the near future that is why avoid mistakes and always do your best so that you won't end up regretting in the end. :)