Shamsher didn't attend the wedding

I think the last time we saw him was when Padmini and he got married, signing the papers given to them by that lawyer RK brought to the chawl.

It is Strange, the CV's of MEIEJ, when planning this track of RK's revenge drama, Madhus heartbreak, retaliation of Madhu and now finally their reconciliation, not once did they think Madhu has a father at home, Padmini is not a single parent, they just erased Shamsher Malik from the story now, a huge drama that unfolded with RK revealed his revenge, any father even if he was working elsewhere would come back home and challenge RK, but they had the challenging of RK in previous track already, despite all of their history it wouldn't stop him from returning and raising a ruckus now, so they just decided to pretend Padmini was an alone parent.

I agree, the writers perhaps don't utilise all the characters properly, the storyline they have going at the RK mansion only and nothing at the chawl, making other characters almost redundant, other serials often they show two households. As that chawl household most of them are actors, they could have shown what is happening in their bollywood film careers, what films they are doing etc, as the show is about Bollywood, but the only acting they show is very limited, since Rishbala got together only RK is shown acting.

Yes maybe he quit the show, as they wasn't any work for him.