Gordon Strachan says he tried to persuade Sean St Ledger to sign for Middlesbrough permanently, rather than return to Preston North End.
St Ledger has just completed a three-month loan stint at the Riverside and was expected to join Boro in a £4million deal in January.
However, after making 15 appearances for Boro, St Ledger is back at Preston after failing to settle in the North East.
Strachan confirmed he attempted to talk the Republic of Ireland international into a U-turn, but understands why St Ledger wants to go back to Preston.
"Having spoken to his family, he feels he'll enjoy his football back at Preston," Strachan told the club's official website.
"First of all, he's been great to work with and socially, as well, I've enjoyed his company.
"For the last two weeks I've tried to persuade him to stay with club. I've tried my best to change his mind, but we respect his decision.
"We left on fairly good terms and have sent texts to each other today. That's all I've got to say.
"Sean has moved on. We wish him good luck and we have to respect people's decisions. We're going to do that and we get on with life."
Meanwhile, Boro have extended the loan deal of Aston Villa midfielder Isaiah Osbourne until early February.