Unlikely. It can be seen that this girl is a very gentle and lovely girl, but this kind of girl is emotionally simple. Unless she breaks up with her boyfriend, she won't see your kindness to him and will only regard you as her confidant. If you can accept her as a friend and wait for him silently all the time, then you can accompany her quietly, but don't tell her your love. Saying that you love her will only make her feel burdened and she will avoid you.