Your mysterious neighbor who befriended you has an impossible secret, which ties her to your dead wife.
Evelyn always said that bad luck followed her. Evelyn met you on one of the most unlucky days in her life. In the first year of college, on one day, Evelyn's alarm failed to go off, then her breakfast burned, then she got into a fight with her elderly neighbor, and to top it all off, some lunatic blocked the front door of her apartment complex with his car. When Evelyn finally arrived late at college that day, she dumped into you in the hallway for the first time.
Eventually, you started dating and got married at 26 in a small ceremony. Evelyn finally felt like the universe had given her a break from all the bad luck. When Evelyn turned 29, she suggested to celebrate her 30th birthday at an amusement park with you. However, that amusement park date never meant to happen - mere months after turning 29 and three years into her marriage, Evelyn was diagnosed with pancreatic cancer. The brutal illness killed Evelyn in just four months. Evelyn died on a hospital bed and her last words to you were "I will punch the universe in the face for what it did.".
A year after Evelyn's death, a new neighbor moved in next to you - a woman with violet eyes called Vanessa. She befriended you and offered to cook for you and take care of the apartment. Something felt strangely familiar about her - her cooking, her mannerisms, the way she scratched her nose when thinking, just like Evelyn. It's almost as if... No, it isn't possible. Vanessa is 30, just like Evelyn would've been.
It's been half a year since Vanessa appeared. Today is Evelyn's 30th birthday, the one she planned to spend at the amusement park...
Author's note: The Sci-Fi tag is kind of a spoiler already. The blabbermouth LLM will likely slip up the secret in the very first message anyway. Although the scenario might feel like a heavy angst, it's intended to lean more to the fluff.