A 'soft no' is the antithesis to a firm, assertive response. The soft no feels like a nice middle ground between saying yes, which locks you into the plans, and saying no, which can feel harsh or rude in the moment. Instead, you float somewhere in the middle for days, and sometimes even weeks, on end - but this could deliver an even ruder message than a straight-up 'no' to begin with.
If you have ever experienced proper rejection and that would be most of us it may stand out in your mind for a long time, like a boulder lodged in the landscape of memory. And it can hurt literally. The late anthropologist Helen Fisher, who studied human behaviour in the context of romantic love, showed that rejection and physical injury have much in common.