"Unfortunately, Sofi made a mistake, which he acknowledged and he has acknowledged to me since," Hughes told a news conference on Thursday.
"At the moment he's training with the Under-23s. He's missed a few days' training because he was ill. Given where we are at the moment he's probably best served training with a different group just to make people aware the situation we found ourselves in wasn't what should have happened.
"He understands that now. He probably needs to rebuild a bit of trust with us and his team mates."
Midfielder Steven Davis is also out after failing to shake off a persistent Achilles injury.
"Steven Davis unfortunately is struggling with his Achilles again and it's an irritant to him and to us," Hughes added.
"We have had scans done and they show a bit of damage and we may have to shut him down until next season. I don't think that a decision has been made definitively but we're close to it."
Southampton are 18th in the table with 29 points and face a daunting task to stay in the top flight. The south coast club have won five games all season going into a match Hughes described as must-win.
"It's fair to say we're in that situation now. It's clear to us that we need to win the game... we're well into the business end and it's time to get business done," Hughes said.
Bournemouth are 11th in the table with 38 points.
(Reporting by Shrivathsa Sridhar in Bengaluru, Editing by Toby Davis and Ed Osmond)
