He probably is really hurt and thinks so negatively of himself because his actions caused his best friend lots of pain amd that imo maybe the reason that he feels that he's unworthy of her... Aslo because of the Goa incident when the policeman blamed him for her plight... it was long time ago but still... sometimes some things leave deep impressions on people's minds...
I'll be able explain this better if I note it in points
~ She took care of him for 12 years that too when he was abroad... Also she singlehandedly managed all his assets and his business perfectly... And he had to kinda struggle with it when he took over ... He even had to take a disguise to get her to crosscheck his budget sheet... He ain't incompetent... He just is really new to all this... 1600 crore ka business handle karna is no child's play...
~ He never failed to admit that she's just beyond gorgeous and though he knows that he looks great too but he knows that Diya isn't someone who goes by appearances...
~ He has seen her dueling with CT with the sword, fighting the goons in the desert alone with her wit and agility, he's seen her using a gun and never did she miss anytime she aimed at something... And ofc the way she managed to counter attack at anyone who tried to attack him or her with words... Thus he knows that she's basically an effing queen and is just the Greek Goddess Athena on earth... And he himself at many times proved to be a fool with his impulsive and callous attitude...
~ He knows that despite all this she still had dreams of a simple yet beautiful life with a husband who'd love her like crazy and support her unconditionally... Also he somewhere feels that she'll only be happy if her husband did things like putting sindoor on her forehead and surprise her with little romantic things which for his age and background (let's remember that he's from London) might seem too lovey dovey to him... And he did try to do that but it made him feel as if he was being fake to himself and to her... He wants her to have a man to whom all this comes naturally... Unfortunately he isn't someone like that... yet...
~ Then in Goa the way the police reprimanded him and said out loud his own insecurities thus confirming that they're infact true (they're true in his head not in reality) and that he couldn't take care of Diya even for a week while she took care of him for 12 years...
~ Also the most important reason is that he is subconsciously guilty that he didn't fall in love with her when she did... and he knows that he's hurt her tremendously though unintentionally... He can't see her breaking down...
These in my opinion are thoughts that are daunting him and in despair he can only see himself at fault for all of this... He's blaming himself and is being very harsh on himself thus he can only see his shortcomings... Which might be the reason of his currently low self esteem...
Indian Idol 15
