@kangarooloo
I wouldn’t exactly say there was a certain part that they fell in love with each other but it was more like Aria caught Asher’s attention with her knowledge about the casino and started becoming enthralled by her beauty and intelligence that eventually he would think of her nonstop. As for Aria, she thought Asher was a strange guy appearing out of nowhere with his over friendly attitude, eventually she realized how sincere and genuine he was about his feelings toward her that she couldn’t help but slowly fall for him. Since all she was used to was guys only wanting her beauty and body, they were never serious about her because she was the daughter of a prostitute.
It was small things that eventually made them fall for each other really.