Alan Dickens says it was a 'tough decision' for Nic Groom to leave Saints.
But the interim head coach feels the scrum-half has done what is best for his future by moving back to South Africa.
Groom has linked up with the Lions in Super Rugby with immediate effect, bringing a near two-year stay at Saints to an end.
The 28-year-old was out of contract at Franklin's Gardens this summer and faced uncertainty.
But he has now put an end to those doubts by switching to the Lions.
And Dickens said: "It was a very tough decision for him to come to.
"It was one I spoke to him about in terms of what was best for him because next year, his future was very unclear and it gave him a chance to go back to South Africa.
"He goes with my blessing and I wish him well.
"In terms of for next season, he ultimately had to make a decision and he's made that decision.
"It helps him going forward and we wish him well."
Groom's compatriot, Cobus Reinach, talented youngster Alex Mitchell and Tom Kessell will be Saints' scrum-half options for the final four games of the season.
It is a big chance for 20-year-old Mitchell, who scored two tries for the Wanderers against Wasps on Monday night, to make his mark, having only played five games for Saints so far.
"It opens up an opportunity for Alex," said Dickens, who was a scrum-half for Saints during his own playing career.
"We are sad to see Groomy go but it gives Alex a chance to show what he can do, perform and stake his claim for next season.
"It will be positive for him.
"Alex Mitchell is a good player and I'm certain he can make the next step."