『あなたの番です』第１２話 has a scene where 黒島沙和, female in her early 20s, comforts 榎本総一, a 14 year old boy.
It is interesting that it isn't「泣かないで」which is what I would expect her say. How can a declarative sentence be used in place of a request/command?
I know young boys are often called 「僕」because the speaker assume their POV when talking to them. Is that the reason why 黒島 says 「泣かない」instead of「泣かないで」here? But the teenage boy is 14, way past the phase when he is addressed as 「僕」.