Disclaimer: I do not own Yu Gi Oh.
By Silver Sailor Ganymede
Rebecca loves Yugi, and Rebecca knows that Yugi loves her too. She knows that for a fact, that they were always destined to be in love, but she knows about something, or rather someone, whom Yugi hasn't told her about.
She knows about the spirit who shares Yugi's body: why, how could she not know? She studies ancient history and, thanks to her grandfather, she knows enough to realise that the spirit of the ancient Pharaoh Atem possesses Yugi.
She knows that Yugi loves her, but she also knows that the spirit of the Pharaoh doesn't: the Pharaoh loves Anzu. Rebecca knows that she is pretty, but she also knows that Anzu, while quite plain in modern terms, looks nothing less than beautiful in the Pharaoh's eyes.
Rebecca sees no problem in this, but there is one major problem she has seen. The Pharaoh is gradually taking over Yugi's body more and more and Rebecca can see that soon, very soon, there will be nothing left of Yugi.
Rebecca knows that she and Yugi are destined to be together, but not in this life, because the Pharaoh loves Anzu, and Yugi has become the Pharaoh.