The Crown Prince Transmigrated, the Heir Was Reborn, and I Got the Short End of the Stick

I had no choice but to be the heir's devoted lackey to complete my missions, and once this one was done, I could finally retire. I chose to be reborn in this world, hoping to live out my life on my own terms. But then I was suddenly granted in marriage to a prince who killed without batting an eye, while the heir who had ignored me in my previous life insisted on marrying me too?! It turned out this world had a bug: everyone had been reborn with their memories intact. And the prince's true identity was none other than the target I had to win over in my very first mission world. Because the target had forcibly escaped, he was also facing erasure by the System. To protect the prince from being erased, I decided to fight the System to the bitter end.