User blog comment:Hayza98/Why did Bella want to become a vampire?/@comment-7600752-20140904064514

This is what another poster said... and I agree:

Bella could have stayed a human, she could have grown up, got a job, had kids, and still been with Edward. It wouldn't have made their love any less real, but Bella kept treating it like she would never be loved by him until she was worthy of him when she was worthy just by being herself.

It's rather sad in reality.

Being with Edward didn't make her want to be the best of herself, it made her want to throw herself out to be someone worthy of Edward. Edward's view of his love with Bella was better than Bella's view of her love with Edward. Bella was really a unexprienced teenager with her love for Edward.

So, Bella basically wanted to become a vampire because she viewed her humanity as something incredibly lowly and far beneath Edward. Bella had to become a vampire so that she could view herself with the same way she viewed Edward.