In Twilight, Bella goes insane when her mother re-marries and ships her off to live with her absent father. In trying to cope with this, Bella imagines a world where she is the centre of attention from every boy in school, especially the hottest, most desirable Edward Cullen. But Edward isn’t just the most desirable guy, no: he’s also a vampire, and sheer coincidence, Bella’s blood sings to him. This should be a problem, because Edward’s supposed to lose control when he comes near a blood singer like his brother Emmett did when he met his: however, Bella’s Edward is so inhumanly perfect that he never hurts her, and even ends up falling in love with her (proof that Bella is insane, because this does not make logical sense to us, the readers, but does to Bella’s poor fragile mind). When Bella realises nothing is really happening with her imagined relationship with some imagined angel-like vampire, she imagines another vampire decides he wants to randomly hunt her just because she’s human (and of course one of the ‘bad’ vampires comes to warn the Cullens of Bella’s danger, because even in Bella’s insanity, random people still care about her). This makes perfect sense in Bella’s mind: she’s never been the centre of attention when living with her mother, and with her father the Chief of Police, he just doesn’t have the time to give her the attention she needs. So she creates the perfect man to love her and protect her and needs her like her parents never wanted, and because she’s never had a boyfriend before, poor lonely soul.
In New Moon, Bella realises her perfect relationship is actually really boring and creates some drama by sending her perfect boyfriend away for her own protection. Or maybe, even in her insanity, she still thinks she’s not worthy so she sabotages her own relationship. She falls into a catatonic state of depression and can only be drawn out of it by the attention of another boy who, coincidentally, is a member of the werewolf pack made to protect humans from vampires. With a suitably heroic new love interest, Bella creates more drama in her insanity by deciding that Edward is going to kill himself over some kind of crossed-wires communication, and it gives her the opportunity to add a lot more drama and an international journey to revive her relationship with Edward. Now that Edward is safe, he tells her she was stupid to believe him when he said he didn’t love her anymore (which of course he does, because in Bella’s mind everyone loves her, even if she doesn’t notice). Now that Bella’s patched up her imaginary conflict with her imaginary lover, she can still create other attention-grabbing conflict by having Jacob still in love with her.
Coming to Eclipse, and Bella’s madness is only deepening. She’s obsessed with herself being the victim, so in some twisted way she imagines that the vampire from the first book’s girlfriend wants her dead, so that for some weird reason Edward would suffer the way the girlfriend vampire has suffered. This is complicated by the fact that Bella is perfect and everyone loves her, especially the vampire lover from the first book and the werewolf boy from the second book. Obviously she can’t have them fighting all the time because that’s OMG DRAMAZ and with the inevitable big fight coming up, she can’t really concentrate on her two boyfriends fighting over her. So in her crazy state of mind, the two boys who hate each other and are sworn enemies make a pact to defend her from the big bad vampire bitch queen – because of course, she’s so unbelievable special.
Breaking Dawn is Bella’s insane attempt at avoiding adulthood while gaining domestic perfection by becoming a wife and mother.
Bella, in her insanity, designs an impossible pregnancy to make her the centre of everyone’s attention. Her mother was never very maternal, so now here’s Bella’s chance to prove to everyone she’d make a better mother than her own mother. And of course she’s insane because apart from the agony of a baby growing to full term in a matter of weeks and breaking her bones and nearly killing her, she doesn’t experience any real motherhood – changing diapers, breastfeeding, teaching baby to talk and walk. But of course Bella seems to get it all in the end: eternally youthful, now immortally gorgeous, disgustingly rich with the most perfect angel-vampire husband and father to a daughter who sleeps at night (unlike her parents) and never makes a fuss or noise and quite frankly hardly needs any parenting at all. It’s Bella’s fantasy of motherhood played out just like she used to when she played with her dolls as a child.
And her reward for being the perfect devoted wife and mother? Immortality. And of course her poor little mind had to make a consideration for Jacob – she couldn’t possibly have Jacob leave her, because he’s her sun or something, and his imprint of the Loch Ness Monster makes him a part of her little cult family forever.