Why did Frodo feel he had to leave Middle Earth at the of ROTK?

so many people who were selfless, brave and apprechiative of everything around them. And i believe this was lacking in the Shire.

Puckey! Hobbits are peace loving, but not cowards. Frodo left because he had lost the innocence that made hobbits hobbits, and did not wish to contaminate them with the darker parts of Middle Earth; much as parents here try to protect their children from the harsher realities of life. There were no flaws in the moral fiber of The Shire, but Frodo had changed too much to ever be happy there again. Even beloved Sam didn't really have a clue about what Frodo had become.

In addition, the physical and psychological wounds that he had sustained rendered it impossible to ever live in The Shire again. Would you expect a young man who had gone to war to come back a year or two later and go back to high school? He had physical wounds that never stopped hurting.........and psychological pain from the Ring. Always a drawing and a pulling at his mind. He had to go to be free of those pains, and he deserved that much at least