Quantum-entangled states underpin many emergent phenomena in quantum materials, yet their direct experimental identification remains a challenge. ${\mathrm{NiPS}}_3$, a van der Waals antiferromagnet exhibiting a resolution-limited magnetic exciton in its ordered phase, has been proposed to host a many-body entangled Zhang-Rice triplet state. Here, using ${}^{33}\mathrm{S}$ nuclear magnetic resonance (NMR) on ${}^{33}\mathrm{S}$-enriched ${\mathrm{NiPS}}_3$ single crystals, we provide microscopic evidence for this charge-transfer state. The ${}^{33}\mathrm{S}$ and ${}^{31}\mathrm{P}$ Knight shifts as a function of temperature reveal a unified spin-triplet configuration arising from strong hybridization between a self-doped hole in the S $3p$ orbitals and a hole in Ni $3d$ orbitals. Furthermore, the ${}^{33}\mathrm{S}$ nuclear spin-lattice relaxation rate exhibits a power-law divergence as it approaches the Néel temperature $T_N=155\mathrm{K}$, indicating critical slowing down of collective charge fluctuations consistent with spin-nematic correlations. These results reveal a spin-charge-intertwined ground state and establish the microscopic foundation for the exceptional coherence of the magnetic exciton in ${\mathrm{NiPS}}_3$.

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• Excitons
• Nematic order
• Quantum entanglement
• Two-dimensional electron system
• van der Waals systems
• Nuclear magnetic resonance