Dave Grohl was reportedly given an "ultimatum" by his wife Jordyn Blum after she found out he had fathered a child with another woman.

The Foo Fighters frontman, 55, went public with his marriage woes last month when he posted a bombshell statement on Instagram revealing he'd been unfaithful to his wife of 21 years and welcomed a love child - now a new report suggests he's doing all he can to make amends to Jordyn.

A source told DailyMail.com: "'He thinks the marriage is salvageable so why not try to fix it?

"[Jordyn] gave him an ultimatum to figure it out and he wants to regain her trust. He has to focus on her, that will be his best chance at getting back to what they had. Dave is focusing on her needs."

The insider went on to claim Jordyn knew about her husband's new baby long before the rest of the world found out - and going public with the news was one way to help rebuild the trust between them.

The source added: "Revealing [the affair and the baby] in the first place was his last-ditch effort to save the marriage, because Jordyn knew about it well before the world found out.

"He would rather remain married."

Dave's band cancelled a planed festival appearance in the aftermath of the drama and the insider claims it was also part of his plan to assure Jordyn she is his number one priority.

They explained: "He can always go back to [recording and touring] if they [the marriage] get better. She hasn't felt like she has been number one for a long time."

Dave – who has daughters Violet, 18, Harper, 15, and Ophelia, 10, with his Jordyn – confessed on Instagram he had a fourth child outside marriage.

He wrote: “I’ve recently become the father of a new baby daughter, born outside of my marriage. I plan to be a loving and supportive parent to her.

"I love my wife and my children, and I am doing everything I can to regain their trust and earn their forgiveness."

Dave did not reveal the identities of his mistress or their child, and signed off his admission with by saying he and his family were “grateful” for the public’s “consideration toward all the children involved” as they “move forward together”.