The 28-year-old full-back was directly at fault for Wilfried Zaha's winning goal at the Riverside Stadium on Saturday, but Karanka claims that no one at the club blames Friend for Boro's first league defeat of the season.
"George is the son every mother wants to have, the husband every wife wants," said Karanka. "George is amazing.
"When I say how proud I am of my players, he is one of them. When I came here, he had come from Doncaster, the club at that time was going to League One, and for me to have players like him on the pitch is a pleasure.
"We win as a team, we lose as a team. To blame one player or two players or three players, I don't think is fair. We are in the table with five points because all of them have been doing really well.
"The player who makes a mistake, they know, and I know when I make a mistake. You don't need to tell him about the mistake.
"We have to think just about the following game, to think we have to fix those mistakes and keep going."
Boro, placed ninth on the table, next take on third-placed Everton at Goodison Park on Saturday.