Why does God not allow me to repent of sex, even though I pray to Him for it?

Allah Almighty commanded repentance and urged it. Sincere repentance is that which involves no return to sin thereafter. Whoever repents with a truthful repentance that fulfills its conditions, Allah will accept his repentance, no matter how great his sin. The conditions for truthful repentance, if the sin is between a servant and his Lord, are: abandoning the disobedience, regretting it, and resolving not to return to it. If it relates to the right of another human being, then, in addition to these, restoring the right to its owner or seeking his forgiveness is required. A person may fall into the forbidden despite his repentance because he does not take the necessary precautions to avoid it, such as letting one's gaze roam freely or secluding oneself with non-mahram women, which are steps of Satan leading to immorality and wrongdoing. Let the servant be truthful with Allah, so that Allah may be truthful with him.