What is the ruling on repeatedly repenting from watching pornographic films and then relapsing, given that the questioner is engaged and hopes for chastity through marriage?

You must initiate repentance by feeling remorse, ceasing the sin, and resolving not to return to it. Seek Allah's help to divert you from misleading desires and to keep you firm in obedience. Follow bad deeds with good deeds, such as maintaining the five daily prayers at their prescribed times with the congregation, avoiding bad company, engaging with the Book of Allah through recitation and contemplation, and hastening to marry.

Among what helps you remain firm in repentance are: constantly remembering Allah, striving in supererogatory acts of worship, listening to beneficial tapes, reading useful books, contemplating Allah's names and attributes, reflecting on death and its horrors, and being mindful that Allah is observing you. Know that the pleasure of sin is fleeting and leads to distress and hardship, and that a servant's comfort and joy are only found in remembering and worshipping Allah.