Vaishnava Samhita. Shri Vyasadasa Charitam I. Vol II Book VI Chp 2 Shloka 8

सौरतं दिव्यदम्पत्योर्द्रष्टुं नार्हति कोपि च

गोपीभावयुतैर्भक्तैः श्रूयते नूपुरध्वनिः   ||

No one is eligible to witness the communion of the couple, Radha and Krishna. Only the sweet tinkling of the anklets of the pair is heard by a few devotees nurturing prema bhakti.