Is saying, "Why did Allah do this to me?" or "Why did Allah decree this upon me?" considered disbelief (kufr), and what is the ruling on the marital relationship in this case? Is it necessary for the wife to review [her faith] or renew the marriage contract after repenting from this sin?

This statement – "Why did Allah do such and such?" – if it is an inquiry about wisdom accompanied by submission and acceptance of the divine decree, then it is not disbelief (kufr). However, if it is an objection to Allah's command and judgment, then it is disbelief, because it constitutes a rejection of the ruling of the Book, due to the Almighty's saying: "He is not questioned about what He does, but they will be questioned." Judging a person to be a disbeliever is not for individuals but for the Sharia (definition) judiciary. If the husband commits disbelief, the marriage is annulled, but if he repents and returns before the wife's waiting period (iddah (definition)) expires, the marriage remains valid and does not require renewal.