Couthino is a special player though - as was Suarez whom they sold.
I can absolutely understand Klopp's reluctance to sell Couthino - if they sell him they're screwed - post sale - not a top 4 title contender - and there's little chance that they could transform thier squad following his sale no matter how much they realistically get.
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On the other hand, if Couthino wants to leave - keeping him against his will, will almost certainly screw you too.
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This late in the window - I'd refuse to sell.
In the winter window - I might consider a sale provided that some other transformative players go on the market. This is almost certainly not going to happen.
Not sure how many years Couthino has left on his contract - but if it's at least 3 - I'd probably sell him next year.
Like all cults - no one is allowed to leave.