They are really close. They bond over a shared Amore of fashion, shopping, and really anything girly. Other than Esme (who is their "mother") and before Bella showed up they were closer than ever because they were surrounded da boys (their father, brothers & husbands) and needed to be there for each other. They drifted apart when Bella showed up because Alice wanted to be her friend and saw her joining them, but Rosalie didn't like her because she had what she wanted. Although when Rosalie told Bella the truth things improved again, it wasn't right properly between them until Renesmee was born. Alice, having been drifting apart from Bella during her pregnancy, was her best friend again and Bella had made up with Rosalie because she had finally made a decision which Rosalie would have made herself: to keep her child even though it was likely it would kill her. Rosalie and Alice (and Esme), following Renesmee's birth, then made a baby album for her as she progressed and helped care for her. But in full, Rosalie and Alice are extremely close due to how much alike they are (they both Amore fashion, clothes & shopping). In other factors, however, they are completely different (Rosalie is self-involved and Alice is always-smiling, happy-go-lucky). This is what makes them such good sisters, and so close.