How Intense can Longing be?

How intense can longing be? It could be just that momentary impulse you feel across a distance to lean against someone. It could be the way the heart flips away at the memory of hands that led your little feet across new sands. it could be just an unfulfilled moment which just happened to pass by unfulfilled. Maybe just an unacknowledged sentiment. Or just a missed hello. Or an unsaid goodbye.