Love between a couple is so much more than just butterflies and romance , it's the respect and thoughtfulness you have for each other which translates into everything and onto every other relationship making it complete . The foundation is cracked here- there is no thoughtfulness and respect. Which explains why Dev never reacts , just lets it slip like water on his back as if nothing happened when his own family members speak ill about Sona.
The manipulativeness of ish needs an applause though- wow she does things without leaving fingerprints!
PS : don't have high hopes wrt any major confrontation between Dev and sona when she hears Aunty!