Is the husband's abandonment of his third wife and his failure to treat her justly compared to his other two wives—especially after discovering the infidelity of one of them and not punishing her accordingly—pleasing to Allah?

Justice must be observed between wives, and it is forbidden to prefer one over another. A woman's request for divorce without harm is not permissible, unless the husband is oppressing her or not being just between his wives; in that case, she is permitted to request a divorce. As for accusing a Muslim without proof, it is not permissible. However, if there is proof that the husband's wife committed immoral acts and the husband was content with that, then it permits you to request a divorce from him.