I've Sworn to Be in the Afterlife, but It Became a Mess After Reincarnating

Long ago, a princess and a knight fell in love, but couldn’t be together. They promised to meet again in the next life where they could freely love each other, but there’s a problem–they weren’t reborn in the same year! Now the princess, a 39-year-old single woman living in modern Japan, just bumped into the reincarnation of her beloved knight: a 17-year-old high school student who recognized her immediately. To her surprise, that teenage boy is determined to sweep her off her feet again, and she has no idea how to deal with that!