I will never marry you.
Never will I marry you.
You are the last man I am willing to marry.
Under no circumstances will I marry you.
If you were the last man in the world, I would definitely remain single.
If you were to marry me, I would go to the temple.
If the sun rose in the west, I would marry you.
I will marry anybody but you.
I can suffer anything but marrying you.
If Li Gang were your father, I would marry you.
If you were to marry me, I would jump to the water/river/lake/sea/well.