I been thinking about the game. And the Unversity Scene. When Joel falls off the horse and is near the brink of death. I am just speculating.
But what if this was Joel's chance to stop running from his past. And be reunited with Sarah in heaven. And when Ellie sews Joel up. Which saves his life.
It is Ellie who winds up robbing Joel of his chance. And after the Winter Scene is over. And they reach Utah with that (giraffe) scene. When Ellie hands Joel back the picture of Sarah.
He replies to Ellie "I guess you, can't escape your past.Thank You." . That "Thank You" is not one like " Thank You. I am greatful to be alive.". It is actually the Opposite in fact. His own body language says it all.
Just like inside the hospital when Joel saves Ellie. This is when he robs her of the cure and to be reunited with Riley. And they finally reach the settlement and Ellie is distant. And on the cliff before the credits roll... she says "Ok"
Joel's "Thank You" and Ellie's "Ok" has much the same meaning.
I am curious as to what many fans of THE LAST OF US thinks about this theory on these two character's.