It had been three months since Yami left and Yugi hadn't recovered. Physically, it was a shock to his system. HIs body had to get used to only caring for one mind, heart, and soul again. Yugi himself was a shell of a person without Yami. Winning the Ceremonial Duel was supposed to symbolize his strength and independence, but it only made him weaker and emphasized the codependence he had with Yami.
Yugi hated trying to live as if he'd never met Yami. Grandpa and his friends saw the toll it took on him. They were worried, but Yugi couldn't bring himself to care. He only wanted Yami.
The loneliness he felt was overwhelming. No more soul room, no more reading Yami's thoughts, no nothing. Yugi had never felt more isolated or incomplete. He'd had enough. He had to be with Yami.
Yugi's depression only became more severe. He had lost the will to live and was planning his suicide. He'd set the date and knew exactly how it would go. Hopefully, everything would go according to plan.
Another month later, it was the day of Yugi's suicide date. He'd hugged Grandpa and his friends extra tight that day, knowing he'd never see them again. After school, he went up to his room and wrote out his suicide note:
Dear Grandpa, Tristan, Joey, and Tea,
First of all, I'm sorry. I know I won the Ceremonial Duel, but I just can't go on without Yami. I plan to find him in the afterlife.
None of you are to blame for this; please don't take it out on yourselves. You all know that I'd only be getting worse. It's better this way. You will always be in my heart. Know that I'll be watching over all of you in the is just something I have to do.
Love,
Yugi
Yugi was holding back tears. He aligned his desk chair with his room's ceiling rafters. He tied the rope around said rafters and made sure the noose fit his neck properly.
"Goodbye," he whispered. He hoped that Grandpa, his friends, and Yami would forgive him. With his last breath, he stepped off the chair and into the afterlife.