What are the reasons for distancing oneself from God and lacking devotion in prayer after a period of guidance, and what is the way to return to closeness with God and to rid oneself of the love of this world and boasting about outward appearances, especially in a society that encourages such things?

This feeling is an indication of the soundness and vitality of your heart. You need to have a good opinion of Allah, rely upon Him, and avoid obsessive thoughts. Be diligent in sincerity, strive in acts of worship, occupy yourself with memorizing the Quran and seeking Islamic knowledge, keep company with righteous women, constantly remember Allah and supplicate Him, and combine fear with hope in Allah's mercy and grace. Have a good opinion of Allah, and know that He is as His servant thinks of Him. Do not abandon a good deed for fear of showing off, and abandon negative thinking, focusing instead on the positive aspects of your personality.