Jerome Kaino will leave the All Blacks squad and return home to New Zealand immediately after the publication of a "personal matter" in an Australian newspaper today.
New Zealand Rugby confirmed the news in a media statement this afternoon, after Sydney's Daily Telegraph reported he had been cheating on his wife with a former Australian model.
He wasn't named in the team's 23-man squad for the opening Bledisloe Cup match in Sydney.
In the statement, NZR also mentioned new information appearing in Australian media about under-fire halfback Aaron Smith.
"We certainly understand that our game and our players are under public scrutiny and these latest stories are concerning," NZR CEO Steve Tew said.
"As an employer, we will take some time to assess this. While NZR does not wish to comment on individual behaviour, it is clear that this is really hurting rugby, all the people concerned, our fans and supporters."
"We take these issues very seriously, and are also mindful that these issues affect people with families and loved ones."
Smith was in the headlines this week after messages between himself and a woman at the centre of an incident at Christchurch Airport were made public.
The woman also spoke to TVNZ 1's Seven Sharp about the situation.