In 23 BC the brother of Marcella, Marcus Claudius Marcellus, died and thus widowed Marcella's maternal cousin Julia the Elder. In 21 BC, Agrippa divorced Marcella to marry Julia the daughter of Augustus.
Marcella's brother's death in 23 BC led to Julia the Elder becoming Marcella's maternal cousin. In 21 BC, Agrippa divorced Marcella and married Julia, the daughter of Augustus.