I'll try to keep it short and to the point although the back story is kind of key for the setting up the dilemma.

Political revolution. 3 key players. #1 betrays resulting in the death of #2 and his wife; their 'baby daughter' survives and is taken by #3 (female who is in relationship with #1). #1 is the betrayer (#3 female was unaware until the betrayal but she killed #2 as #2 was about to kill #1).

#3 raises the girl as her own. Trains her in martial arts so that she can avenge her parents and kill #2 and #3 (doesn't reveal that she's #3 until coming of age). But yes, basically #3 is raising the daughter and teaching her the skills to kill her, #3 and primarily #1.

Coming of age, the girl goes off on her own after being told the full back story. Next time the girl and #3 meet, #3 says, one of them will die.

Skip to finale ending: basically, the girl finds out that she isn't the daughter of #2 (who died from wounds during the original betrayal). She's actually the daughter of #3!

#3 despises #1 for the betrayal but still loves him and wants him to pay for his sins just like her. Die together and be together.

#1 and the girl engage in a fight. #1 is strong and likely would win in the end. But #3 enters into the fight, hugs #2 and says suggests it's time. #1 drops his sword. They remain hugging with the girl next to them.

The dilemma: #3 wants to die with #1. Pay for their sins. #3 raised the girl just for this. The girl was raised for this, only recenlty learning that #3 was actually her real mom, not just adopted mom. And now realizes that #1 is her father and that #1 and #3 love each other.

What's a girl to do? For me, tear jerker ending......