Prince Harry is “heartbroken” to step down from his role with the Sentebale charity.

In a joint statement released on Wednesday, the Duke of Sussex and his co-founder, Prince Seeiso of Lesotho, explained their “devastating” decision.

The two, who established the African organization in 2006, cited an “untenable situation” involving chairwoman Dr. Sophie Chandauka and the board of trustees as the reason behind their move.

“What’s transpired is unthinkable,” they told the London Times. “We are in shock that we have to do this.”

“With heavy hearts, we have resigned from our roles as patrons of the organization until further notice, in support of and solidarity with the board of trustees,” they continued. “It is devastating that the relationship between the charity’s trustees and the chair of the board broke down beyond repair.”

Harry, 40, and Seeiso, 58, explained, “Although we may no longer be patrons, we will always be its founders, and we will never forget what this charity is capable of achieving when it is in the right care.”