I'm not so worried about the new girl because whatever drama happens, Malhar's heart always belongs to his Kalyani.
He may decide to leave AN because of his guilt over what happened with Moksh and /or Kalyani.
Malhar's side has weakened now with Moksh missing or presumed dead, Kalyani presumably injured and also because Sarthak has been stabbed by Trilok as per precap. Anupriya and Swara don't have much of a voice.
Deshmukh's side is gaining strength with the entry of Nal and probably even Vivek and Goda. Pallavi will definitely turn chameleon.
From yesterday's entry of Nal my guess for Malhar leaving AN can be this too -
Nal was shown to be driving a stolen car. He's clearly underage, doesn't have a licence and is not even sure if he could drive properly.
I'm sure he's not going to catch Trilok as precap showed Trilok in AN.
With his poor driving skills, the boy may cause an accident.
AS and Pallavi may expect Malhar to cover it up as Nal actually drove only to chase Trilok and get Moksh.
Malhar may not be in a position or right frame of mind to help them. It would be a case of stolen car and rash driving without licence.
This can turn AS who is right now too sweet, against Malhar. She may literally drive an already guilt ridden Malhar into more guilt and he will leave AN and /or Aurangabad.
I feel Malhar may not exactly resign or leave the police force but probably take an hiatus.