Flash marriage rich sickly little milk dog, upgrade to fight monsters

The stingy boyfriend of six years invited her to dinner at a luxurious restaurant. It was not a proposal, but a breakup. The heroine was afraid of wasting the expensive red wine, so she drank it all by herself. Then... she said to the hero: You are so beautiful! Marry me! The hero said: OK! Tomorrow when you sober up, we will go to get the marriage certificate. After sobering up, the heroine regretted it. Because the hero is five years younger than her and is still studying. But the hero refused to do it, saying: Sister, my mother died a long time ago, my father remarried, and my stepmother gave birth to a son, so I am all alone... The heroine softened her heart and got the marriage certificate with the hero. But slowly she found out that the hero was the heir of a wealthy family, and his father had never changed...