The two met for the first time on the battlefield and got married for the sake of national peace.
"We are just getting married, I advise you not to have any wrong ideas."
"You can rest assured that this princess is not interested in you."
Many years later, the war resumed, but the two could not go back to the past.
See you again on the battlefield, but it feels like we have met for the first time
"You saved my life, and I'll give it back to you this time. I don't owe you anything anymore."
"You really want to save her, no matter the cost."
…
"If I could turn back time, I would rather not see you, not miss you, not fall in love with you, not let you down, I just want you to have a safe life."
Concept: The male and female protagonists have the world in mind