I think I finally understand. Anu is back to ensure Tanni and her family are well taken care of. Once they have the shop up and running he will marry this other girl whose father is a bigger businessman that his own dad. This will help him achieve his goal of being better at business than his father.
He hasn't fogotten his love for Tanni, he is sacraficing it to teach his dad a lesson. He also knows Tanni promised to let him go if he found himself in love with another girl and she will keep her promise. That is why he isn't showing his love - he probably thinks it will hurt her less.