I Don't Deserve You (A Johnlock Fic)

Why did Sherlock do it? Was he depressed? I know I'm not a genius like him, but surely I would have noticed something like that - After all, I've been in love with the worlds only consulting detective since I first laid eyes on him.

After Sherlock commits suicide John is plagued by guilt and regret, he should have noticed if he was depressed, he should have told him he loved him, he just should have done MORE for his best friend.

Set after season two, this doesn't follow season three but may contain spoilers