To me his changed character seems similar to Jacob black from twilight (I know...a really strange comparison). Even Jacob wanted bella and made it clear that if she wants to be with Edward then she can no matter how much it hurt him, but he always claimed and reminded bella that he loves her more than Edward does and if she ever changed her mind he would be there waiting for her.
This reminds me of yuvi, as it seems he is trying to say to twinkle that he doesn't mind now being her second/ backup choice and if she ever changes her mind about him and feels he truly loves her more than kunj then he will be waiting for her. Even yuvi's love is as cuckoo as his obsession for twinkle not to mention bat-shit-crazy