Star's dead. Mewni destroyed. Let's add Toffee to the collection of dead people.
Star's death was a tragedy, Marco unable to move on, finds himself in another one of those helpless situations only, no Star to help him. Stick by him. Support him.
Marco struggles to fight through this journey until one day, a girl comes to his life. Marco doesn't exactly know what the girl did to him, either made his life better or worse. He believed in the latter one. But he finds himself wondering if that was the real output.
And what's made it more confusing is that, the girl...was someone he knew before.
"S-star? I-I thought you were dead."
"Oh but I'm very much alive, Marco."
Disclaimer: I do not own the show Star Vs The Forces Of Evil, this is my original plot though. I only own some characters that weren't on the show!