All this is the reason why karthik compels himself to stay away from survi; he in a way is actually doing this as a punishment for himself for the wrong he feels he has done to his brother. Karthik said himself today that nobody has any idea how it feels when you finally attain the happiness you have been seeking all your life and despite that you cannot fully accept the happiness life has given you. Karthik thinks that despite finally getting some happiness in life, he feels he has been deceived and rendered helpless by fate to reject that happiness and push it away from him as he feels he is not deserving of it and that his brother has the right over that happiness.
Karthik has always been the kind of person whose actions are driven by his conscience and he is unable to bear the responsibility of hurting his beloved brother on his conscience, hence why he is acting out of character. What karthik does not realise though is that he is punishing poor survi without any fault of hers, but to him survi has benefitted from this entire incident and aniket has suffered so he is less sympathetic towards her and is prioritising aniket's happiness and best interests over survi's rights as his wife as well as overlooking and supressing his own love and desires for survi.
Karthik is in quite a dilemma but today's precap for tomorrow's episode has made me have more faith in him as he spoke up in favour of survi in front of the almighty tai who he would never speak or listen to a word against. He showed faith in her that she was not capable of doing such a disrespectful thing as causing someone physical harm. Survi in karthik's eyes is the most innocent person in the world who can never harm or think ill of someone, that is why regardless of how much he worships tai and thinks she can never do wrong, he similarly has blind faith in the fact that survi is incapable of hurting anyone and trusts her in every way except from when it comes to survi herself speaking against tai.