Is a marriage considered valid if the offer and acceptance were made via a WhatsApp conversation, without awareness of the presence of witnesses, and is divorce necessary in this case?

A marriage contract through modern communication methods like phone, internet, and the like is not valid. This is what the Islamic Fiqh Academy has ruled. Among the most important conditions for marriage are the presence of the guardian and witnesses, and their attendance at the contracting session. A contract that takes place without a guardian and witnesses is null and void by the consensus of the four (Sunni) schools of thought. Separation in such a case requires either divorce or annulment. If the husband does not issue a divorce, the Sharia judge shall annul the marriage and separate the spouses.