What is the reason for the recurring discontinuation of prayer despite feeling remorse and returning to it?

The feelings of remorse, anxiety, and distress you are experiencing are due to abandoning prayer and turning away from the remembrance of Allah. Allah the Almighty says: (But whoever turns away from My remembrance - indeed, for him is a constricted life, and We will gather him on the Day of Resurrection blind.) [Taha: 124]. Abandoning prayer is among the gravest evils and a cause for Allah's punishment. Allah the Almighty says: (Then succeeded them later generations who neglected prayers and pursued desires; so they are going to meet evil.) [Maryam: 59]. You must hasten to repent, be diligent in prayer, keep away from bad companions and detrimental environments, and return to Allah with determination and sincerity.