First the Karvachauth flashback.... It was Armaan who she would've seen after seeing the chand had he not moved out of the way deliberately for Sid.... so he changed destiny for her happiness....
Second, the duppatta scene during the striptease.... it would've fallen on Armaan had he not moved out of the way for Sid.... so he changed destiny again for her happiness....
Apart from these hints, the obvious fact that he is deliberately convincing Riddhima to forget him and try n accept Sid, creating and orchestrating situations for them to get closer to one another, deliberately keeping himself away from the woman he loves so much.... all against what destiny has in store, against what signs he's seeing, against nature, against destiny....
why?? coz he truly loves her.... coz he loves her selflessly enough to give it all up just coz he thinks she will be happier without him.... thats what is the true meaning of love!!
Please no bashing, I am just putting forward a point of view....