So i think when he got his mom's flash back he realized what she meant to explain to him then, made him realize he was not insulting her in any way as rose is not at fault and that's when he remembered all his moments with Kushi. He realized she is more to him then his past or hate. If i remember correctly he was never angry at the other women. It was always his dad's fault for him. I feel he made a decision by time he returned.
By Nafrat, Dhoka, Dard i think he meant that coming there he knew his past will be in front of him to taunt him. Even though he knew that his past will give him pain if he comes there. He was ready to get over it and be with her. I feel his moving back is mainly just CV's creating tension. But one explanation is he wanted to complete saying what he wanted to tell her before her concentration diverts to his injuries. So after holding her he completed saying that "He was searching for answers to question for which she was the answer (her Love)".
When he said about Rose and thorns to Dadi. I think he meant thorn is his father and not Garima. From his past experience with Kushi and Shyam it must be easy for him to understand Garima's situation. He started trusting people.
I really think he is moving forward as Arnav/ASR always do everything face to face. He is a man who is not scared/afraid to say and do what he wants. So no it will not be ASR if he is doing everything with other motives in mind. I really hope CV's don't go down that way. We already have scammer in the serial (Shyam) who is two faced. I really don't think and want hero to be two faced.
This is how I looked at it. I hope I am not wrong😛