Although Farrell has never directly blamed social media abuse for his decision, and Borthwick was careful with his choice of words on the matter at a media briefing on Thursday, comments from both men have indicated that its impact on him and his family played a large part.
"The first thing I’ll say is that I’m full of admiration for this guy, as a man, a player and a leader," Borthwick said. "It takes a lot of courage to do what he’s done.
"In England alone we’ve seen a player - the captain - and two match officials step away at the top of their game because of certain issues. There are societal issues here that are going on. The online hate that is spread is not ok, it’s not right."
Asked if he expected Farrell to return, Borthwick said: "I am really hopeful he does. This is one of England’s greatest-ever players, greatest-ever captains. I made it really clear there is no pressure on him, that’s his decision, at the time that’s right for him.
"Any team in the world would miss an Owen Farrell but the work he has done to help create a foundation over these last months, to help re-set the England team and move forward, that is part of his legacy through this tournament."
With Courtney Lawes (34) also retiring, permanently, from internationals, Borthwick will announce a new captain on January 17th when he names his squad for the Six Nations championship.
SERIOUS CHALLENGE
Having also confirmed defence coach Kevin Sinfield (43) will leave after this year's tour of Japan and New Zealand, Borthwick believes England are ready to kick on from their third-place World Cup finish and make a serious challenge for the Six Nations title after several years of lowly finishes.
"Just over 12 months ago I said that this England team had no area of its game that was within the top few teams in world rugby. That was the reality," he said.
"What's happened is building that foundation to make the team competitive and I think I think everybody can see that's what's happened.
"Now you need to keep strengthening that foundation and to evolve and develop - this is the next stage. There are some changes in the coaching team, changes with some players and there will be some changes tactically, that's a necessary part as we as we build.
"From my point of view, I think it's exciting to look forward to what those next steps are."
One player who will not be part of Borthwick's plans, for the next two years at least, is Henry Arundell (21), after the exciting winger extended his contract with French club Racing 92 rather than sign one of the RFU's new hybrid contracts and join Bath.
"I said to him: 'Henry, I’m really disappointed, because I want you to come back to England and I’d love to see you in the England shirt, but I want you to do well'," Borthwick said.
"He was very clear that he wants to come back for the 26/27 season and he wants to play for England at the next World Cup.
"I can see him being an important part of the England team over these next seasons and building up that experience and I'll be tracking him."
