A voidable marriage is still a legally valid marriage
A voidable marriage is one in which the marriage was in some way technically deficient, such as the original marriage certificate was never filed or the wrong name appeared on the marriage certificate.
While the marriage is technically deficient, it is not, per se, void. The legal defect can be cured unless one or both spouses want to annul the marriage through a summary process called annulment. If not, they will remain married.
The marriage does not require a divorce because there was never a legally valid marriage. This is considered a voidable marriage.