Interviewer grinding me down
Solution 1:
I'm sure you understand that whichever of these you choose it will be a metaphorical use of the term 'grinding'.
'Grind' is a verb with a physical meaning of which I feel sure you are aware. 'Grinding down' is an idiomatic expression used for people and situations that tend mentally to exhaust one. 'Work grinds me down'.
'Grinding' on its own is less commonly used metaphorically, but that does not mean it is impossible to coin phrases which contain it.
'The daily grind' is an expression of hopelessness and the inevitability of work and its attendant miseries.