think maturity is playing cards here...arnav is able to differentiate...though he announced his engagement out of anger, when he realized that kushi'll haunt him forever, he was ready to give in...(though its known only to him...) first defeat of asr...he thought of getting engaged to prove a point to kushi...but, his love defeated his ego...so, arnav knows it...
kushi, a girl who is naive and who's yet to explore the world...love is like a alien for her...her mind has been preoccupied with her family. she has to bear the responsibility...had arnav been in this position, he would have never realized...but, kushi is able to sense something but she doesn't want to take it further...after that diwali night, kushi's heart has been shattered...
so, its the duty of arnav at this point to love her more...he should go behind kushi to make her realize her love...