It would be difficult to argue that the love between Bella and Edward is not valid and true. Several reasons prompt this. In my mind, the most overwhelming of these resides in how both characters wish to escape their condition to be with the other. When it is evident that both inhabit different worlds that post a natural impediment for their affection to be realized, their desire to transcend this creates a setting where their feelings for one another have to be real and substantive. They both dislike their conditions and are willing to abdicate them to be with the other. Edward realizes the curse of being a vampire in that he cannot truly be with Bella, who for her part is ready and willing to sacrifice being a human in order to be with him. The notion of wishing to transcend condition reveals that there is a conception of love present that is true and valid. Additionally, there is also a sense of loyalty to one another present in Edward and Bella that seems to indicate the presence of true love. Despite the circumstances that are thrown in their respective paths, one can tell that there is a genuine sense of loyalty and pure recognition of the other, revealing a source of true love.
They love each other because Edward showed his true self and had no intention of hiding himself from Bella anymore. He wanted Bella to know who he was but also wanted her to be safe.
The love they have between each (for myself) became more prevalent when Edward took Bella to the meadow and showed her his true self. Edward didn't try to continue hide who was and what he was he made sure Bella got that. Then Bella boldly told him that she didn't care what he was she'd still like him. That's just awesome it's true love when both parties can accept each other even when they're entirely different.
There is no doubt that the love between Bella and Edward is true. Several evidences are present in the book that points to that.
a) Edward hates being a vampire after falling in love with Bella because he is afraid he will hurt her physically and emotionally
b) Bella would give up everything to be with Edward and she is even willing to become a vampire for him.
c) Edward protects Bella from harm, e.g. the car accident in the beginning of the novel
d) They have unmistakable attraction for each other
e) Although Bella knows its extremely dangerous being with Edward, she would risk it just to be close to him
These evidence clearly point to the fact that Bella and Edward are truely in love with each other.