It's not as if the Queen was responsible for Diana and Charles's behaviors that led to the estrangement that led to the disgraceful interview that led to the purported advice to divorce. Even if the Queen had so advised, we weren't there, and we didn't hear whether she advised them to "obtain some kind of counseling and try to reconcile for the sake of the children or else it will end in divorce", at which point Charles and Diana said, "She told us to divorce!', shifting the blame elsewhere for their own stupidity, which is the more likely scenario.
Charles and Diana are both prominent protagonists and prominent victims of the "sex, drugs, and rock'n'roll" cultural revolution that was surrounding them and the Queen, of which the rise of the Beatles, the Stones and tabloid culture (thanks to Rupert Murdoch bringing it to UK) played a large part. She cannot be solely blamed for the actions of her adult sons.
During the interview, Diana questioned Charles’s fitness or ability to be king. That was probably the last straw for the queen.