The summer signing midfielder was not selected by boss Brian McDermott for last weekend's 3-3 draw with Fulham and is now not certain to be involved in Sunday's Premier League basement battle at Queens Park Rangers.
Guthrie has discussed the subject with his manager but has also reportedly snubbed a loan move to Nottingham Forest, as he remains fully committed to Reading.
He said in the Daily Mirror: "I spoke to the manager and he had his reasons for not picking me and that remains between us - there was no bust-up.
"It is frustrating, because I want to help this team. I just have to work hard for now and make sure I am ready and fully prepared when I am needed."