Having rejected a new contract with the Toffees, Barkley came very close to joining Chelsea on transfer deadline day but changed his mind late in the process after travelling to London to complete a £35m move.
With his contract winding down to its expiration next June, there is plenty of speculation regarding a potential switch to Stamford Bridge or, perhaps, Tottenham Hotspur in January but, for now, he is on Everton's books and eligible to play once he regains his fitness.
Barkley has been sidelined all summer following surgeries to his groin and hamstring and is not expected to return to action until the end of November.
Whether he is eased back into the team in spite of his desire to leave the club will be up to Koeman but the manager says he isn't thinking about that yet.
"Ross came to see me on Tuesday and he explained to me why he turned down [the chance] to go to Chelsea," Koeman told the media today.
"That is a private talk with Ross and I am not the right man to explain to you about his decision or the reason for that decision.
"He was open to make a move to another club and from what I heard from the board, there was an agreement between Chelsea and Everton but finally the decision was [made] by the player and, finally, that is what happened at that time."
”He is still an Everton player and, to the end of this season, he has his contract. At this time he is injured and it will take another two to two-and-a-half months until, maybe, he is available.
"I don't have to take that decision now. I can wait to see what happens and then we will see what the decision will be at that time."