Pakhi was the one he always wanted but lost.
Sai was the one he was burdened with.
He taught himself and made everyone believe that he could love Sai
But in reality, he never moved on from the fact that he lost the first girl he ever had feelings for.
So, he kept choosing her over and over and over. The only reason he waited for so many years to consummate was the blindfold he made himself wear "he loves Sai"
He never did. He believed he did. Everyone knows he never did. And he never will. Sai was something he had to live with so he was trying to make best of the situation.
That's why he was angry to see Sai alive instead of being happy, he thought his unwanted burden was back.
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