Backs coach Matt Sherratt will leave the Ospreys at the end of the season, a year before the end of his contract.
The 43-year-old has asked for an early release in order to spend more time with his young family.
Sherratt joined Ospreys from Cardiff Blues having earlier had spells with Bristol Bears and Worcester Warriors.
"It's been a tough decision but the right one for my family who must come first," Sherratt said.
"I've loved being part of the Ospreys set-up, and remain absolutely committed to our collective efforts between now and the end of the season."
He added he would take time to decide on his next job move.
Ospreys have been hit by international commitments and injuries during a difficult start to the season which has seen them lose six of their last seven matches.