Why does a worshipper who is diligent in observing the Sunnah and performing night prayers feel no progress in their relationship with Allah, while seeing those around them surpass him in this closeness?

Feeling deficient in obedience is a positive thing that motivates one to work and improve. This can be achieved through: associating with the righteous, not overindulging in permissible things, maintaining remembrance (dhikr), compelling oneself to obey, self-accountability, frequently reciting the Quran with contemplation, remembering death and what comes after it, seeking religious knowledge, giving charity and being kind to people, and making supplication (du'a).