Let me start by saying I know the answer and just want to know what you think?
God would of let him eat of the forbidden tree had he been faithful. The fruit of this tree would of granted him everlasting life. Sadly we suffer from his disobedience and this is what God said:
(Genesis 3:22-24) 22 And Jehovah God went on to say: "Here the man has become like one of us in knowing good and bad, and now in order that he may not put his hand out and actually take [fruit] also from the tree of life and eat and live to time indefinite,--" 23 With that Jehovah God put him out of the garden of E?den to cultivate the ground from which he had been taken. 24 And so he drove the man out and posted at the east of the garden of E?den the cherubs and the flaming blade of a sword that was turning itself continually to guard the way to the tree of life.

God will restore mankind to his original purpose and we will get to live forever in paradise if we are obedient. Please go to website below and find out how we will be delivered.

http://www.jw.org/en/publications/books/bible-teach/why-does-god-allow-suffering/