>>87082258Eventually Star goes back to Mewni while Marco stays behind. They keep in touch through trans-dimensional mirror calls and occasional visits using the dimensional scissors, but over time these become fewer and fewer as they become more and more busy with their own lives. Star is groomed to become Queen, Marco gets a job.
One day they wake up and realize it's been years since they last called the other, and they consider making the call, but figure the other is busy with their other lives. The years pass.
Star chooses a King consort. She becomes Queen. She has a daughter of her own to eventually pass down the Wand.
Marco works hard at his job. He gets that raise. He gets that promotion. He has a fling with that secretary that he is sure is stealing his office supplies. He has kids of his own.
Many years later they see an old memento and reminisce for a moment, but in the grand scheme of things they find they don't really miss each other that much.