He died a virgin. He had planned to wait. Wait until he got married; wait for the perfect girl (or guy). And wait he did.
Yuugi Mouto had come to the decision when he was ten. Upon hearing rumors about the nature of sex among his classmates, he had grown curious. None of his peers would explain, chalking it up as another one of his weaknesses. So, he had gone home to ask his grandfather. After a lengthy explanation of certain actions between two people who were in love (or at least in lust), Yuugi had made the most concrete decision in his life.
That nearly changed when he solved the puzzle. It was no surprise that he had fallen for the former boy-king. Atemu was everything anybody would want in a guy.
Yuugi would've loved to give himself to the spirit, but one obstacle stood in his way: The spirit of the Sennen Puzzle had lacked a body. At some point, their soul rooms had been suggested—Yuugi wasn't sure by whom—however, Atemu had said no. Yuugi was not hurt, for he knew the spirit meant no offense. Atemu merely desired Yuugi's first experience to be real rather than something in his mind. Literally.
So Yuugi waited.
As time went on, and the boy-king's name discovered, it became apparent that Atemu would never gain a body. He had died, his body already turned to dust beneath hot, Egyptian sand. Thus, Atemu went on. On to the life after this.
And Yuugi still waited.
His determination never faltered, nor did his desire to live. Yuugi had never been one to give up. More time passed and he matured, along with his friends. He maintained his title for many years, eventually going on to a university. There, he majored in Ancient Antiquities and became the foremost authority in that area.
Yuugi became one of the most eligible bachelors, even through his older years. He was known for his beauty, kindness, and generosity, as well as his odd desire to remain single.
He adopted three children and saw them both through their adulthoods, their marriages, and the births of their own children. Hikaru, Raito, and Yami never quite understood their father's insistence and determination in his decision, but thought it to be connected to a fairytale they had heard as children about a young pharaoh, his beloved prince, and their fantastic adventures.
Hikaru, Raito, and Yami easily forgave their father for his eccentricities: his affinity for a certain well-cared for, yet worn deck of cards, and his tendency to reach for something that might have hung around his neck.
And still he waited.
But one night, something determined that he should wait no longer.
As Yuugi slept on June 4, the night of his 80th birthday,a higher power deemed Yuugi's time on earthwas complete. He never awoke.
And as those he left mourned him, Yuugi found himself on a linen covered bench. Garbed in nothing but a linen kilt, Yuugi realized that his fingers were no longer knotted; his bones no longer frail, his skin no longer wrinkled, and his body that of his former fifteen year old self. Unsure of his place or of any tasks he might have had to perform, again, Yuugi waited.
And then, a voice:
"I'm sorry, Aibou. I couldn't wait any longer."
Takahashi owns YGO. This is my way of coping.