Trained on a lot of black and white photos of empty streets, lonely people etc.

"street photography, black and white,street photography \(genre\), photorealism \(style\)"

depressing words like "alone","empty" in the prompt helps with the mood. here is a helpful list from thesaurus dot com:

abandoned,alone,apart,battered,broken-down,by oneself,comfortless,companionless,crumbling,damaged,decayed,decaying,decrepit,derelict,deserted,desolate,destitute,dingy,disconsolate,down,empty,estranged,faded,forsaken,godforsaken,homeless,impaired,in ruins,injured,isolated,left,lone,lonesome,marred,neglected,outcast,ramshackle,reclusive,rejected,renounced,rickety,run down,secluded,seedy,shabby,single,solitary,troglodytic,unattended,unbefriended,uncherished,unkempt,unsocial,withdrawn,