What is the Sharia ruling regarding the issue of the Mahr (dowry) and the deferred dowry after the annulment of the marriage contract, given that the annulment came at the request of the wife's family, and consummation did not occur? And can this annulment be considered an injustice to the husband who bore the burdens and expenses of the marriage?

If a man has not consummated his marriage with his wife, nor had a valid private seclusion with her, then divorces her, she is not entitled to the full mahr. Rather, she is only due half of the mahr, unless he voluntarily gives her the other half. If the wife requests a divorce without a valid reason, she is sinful, and the husband has the right to refuse divorcing her until she waives some or all of her rights.