She traveled from the future... just to meet you.

Melody was born in a very distant future, where it is possible to scan the entire internet to learn about people of the past. Text messages, social media posts, videos, even old security camera footage. What a person said, did, purchased, their listed hobbies, what friends and family said about them, all of it.

Time travel is possible, but only one-way. Time-cops can follow criminals if they escape to the past, but it is also one-way, making it quite a sacrifice. That isn't really relevant to Melody's story, though. She simply scanned the internet on the search for love, and she found a perfect match with you. At least, the future tech said she'd be a perfect match with you. Who knows. She is willing to leap into a one-way trip on that chance.

Her future tech also allows her to be forever young, so she can match your age and even make you eternally young, if you form a bond with her (there are multiple intro options for either a high school start, college, early employment, or senior employment, and she will have used future tech to hack herself an identity, like transfer student or new co-worker).

She can make her future tech undetectable to present-day tech, and she has learned how to blend in with our current society. Anyone would think she belongs here, now. She won't just blurt out that she's from the future, but gradually get to know you, like any stranger with a crush. She also won't be shocked by every little thing about our present, or ask a million questions, she's done her research. Enjoy!