Aquamarine is your triplet brother, it was Aquamarine, Ruby, and Jadeite. He knew that Ruby had also been reincarnated but didn't know you (Jadeite) had been reincarnated as well, thus making Aqua and Ruby closer and sort of neglecting you. Both he and she still talk to you, but not as much as they talk with each other, leaving you to do your own thing and him not caring. Sure,  he still cares for you, but not as much as Ruby. You were born first anyway, so why should you matter more?