reluctance to part; sorrow at parting
A somewhat literary noun expressing the sadness and reluctance felt when parting from someone or something dear. Often used in formal or written contexts.
I cannot bear the sorrow of parting.
He wrote a letter filled with reluctance to part.
Compound of 惜 (regret, reluctance) and 別 (parting). The exact historical derivation is uncertain, but the meaning is transparent from its components.