The word "moving-on" as many meaning behind it... for guys they can move on easily because they accept whatever life thrown at them....but for girls they can't move on easily because of emotions.
Riddhima is trying hard to show Armaan (few days ago) that she moved on easily with Sid and having him around doesn't effect her anymore...
but
deep down inside girls get jealous easily when they see their loved ones flirting with another girl....
Why?
Because deep down inside they are weak through their emotions (and usually think by their hearts) and now Riddhima is gonna go through that pain because she might be happy for Armaan moving on in life (because he deserve much better person than herself) but love is powerful emotion which can not be spoke only understood through the emotion.
Lately, whatever shown through second season of DMG is sort of based on real life actives... because somewhere today there are girls who are in Riddhima's shoes and there are boys like Armaan...
for them love is biggest and deepest emotion that can not be expressed without making sacrificing for each others happiness.