Now you have to remember, she didn't start school one day and the next day was with Edward. She interacted with these people 5 days a week sometimes more, classes, lunch time, at La Push, shopping. She hung out with them and started relationships with them. Then she was with Edward.Crusader For Literature wrote: Their treatment of her would be reproachable if they were actually her friends and she were actually theirs. If so, firstly she wouldn't have gone zombie, and secondly, they wouldn't have abandoned her. But she literally didn't consider them friends, so their behavior was perfectly understandable and acceptable. She didn't care much about them before edward and not at all after. She didn't consider them friends, only tools to be manipulated if necessary.
Seriously, I think this whole idea sprung from desire to see Bella as this poor victimized soul who had no meaning in her life besides vampires. She wasn't. Not having friends when zombified was her problem and her fault.
I don't view Bella as a poor victimized soul. I think Bella is very independent and strong. But I don't think she is heartless and to feel any less than what she did when Edward left would have been incomprehensible.