His behaviour was not unreasonable. Infact it was completely reasonable and justified under the circumstances.. He is not aware as yet to the many sacrifices Arjun has done for Arohi. Arohi should have sat down and explained everything to him instead of acting so rashly..Initially he would not have listened to her and not believed her.. but she should have kept trying..that's what you do to convince your parents if they are against your choice of life partner...
frankly till now i hvnt seen arohi trying really hard to make hp see her pov abt arjun... may be the scenes n dialogues given to her has not reflected that or whtever she acts really dumb n clueless