Trap of Youth (1999)

Both FL got pregnant at a young age and both of them encountered that their lover stopped caring about them after getting pregnant. The lover of the FL finds another woman eventually betrays the FL and marries that rich woman. Both the FL marries the brother of that rich woman for revenge.

FEmale leads being betrayed by their own boyfriend/husband by marrying rich woman. The female leads fall in love with the brother of the rich woman seek revenge.

>Yoon Hee and Ha Ryu both sacrificed their studies to support their girlfriend/boyfriend college fees
>Both couple have a child out of wedlock
>However, their lover cheats on them and fells in love with rich man/woman
>Both of them plots revenge on them by falling in love with that sibling of the rich man/woman