I think he looked upset coz he got personal and made a dig at her when all she was tryinfg to do was save his relationship with La! She also said some home truths to him like "you never loved her at all, coz if you did, then you could not act this way"!
I think he just lashed out, and then as usual regrets it! He called the security which was over the top (even he knew that)...this was a way to get her out of there and of course naturally she was upset, coz he was calling Security on her when he knows her personally!
So it was a combination of things! He felt bad coz he knew he was a jerk to her! He DOES have a consience that is what they are trying to show us! Even after he yells or insults he is decent enough to know he did wrong! He just dosent know any other way to act coz he has been doing this ASR act for such a long time, he has forgotten how to be just "Arnav".
I found it interesting that in the apology scene when he is talking to himself he says "Just say sorry Arnav, that is all you have to do"! He calls himself Arnav, not ASR! I think that says something! Arnav is a REAL guy and ASR is the ALTER EGO!
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