To miss someone is a yearning desire, an intense crave experienced in one’s heart, a different kind of sorrow felt as one hopefully wish for what he longs for - and at the same time a heartbreaking wait, a melancholic pang, a wistfulness, a disappointing and painful belief, anticipation and expectation.
It is a sadness as one aches to return to a place he calls “home” - or just some place he felt he belongs, as in the German word for homesickness, heimweh; the Welsh word hiraeth, a homesickness for a place you can never return to, or that never was, tinged with grief or sadness over the lost or departed; or the Galican word morriña, a very deep, nostalgic and melancholic homesickness experienced as one intensely longs to return home.
It is a deep sadness as one longs for the memories of the past, as in the Japanese word natsukashii 懐かしい, a longing for the past that connotes both happiness for the fondness of that memory and goodness of that time, as well as sadness that it is no longer. It also refers to a nostalgia for a life or event that one has not experience.
… a deep sadness as one intensely longs for someone, the Romanian word dor, a deep and nostalgic feeling of sadness, agony and emptiness experienced upon intensely missing, longing and yearning for something or someone; or even beyond bearable bounds, as in the Russian word toská (тоска); the French avoir le mal de quelqu’un, missing someone so much it literally makes you sick - “Someonesickness” on the model of “seasickness”, or “I miss her so much it hurts”; or more loosely, “miss someone like crazy”.
… a deep sadness for what one longs for, and specifically the painful emptiness felt knowing its attainment is uncertain, described also in one of the contents of the German word sehnsucht, or the Portuguese word saudade.