In the end, Lolita dies in childbirth, and the child is also born dead. While this can be just unfortunate or a symbol of being neither "allowed to grow up" nor ever having a real future (the stillborn daughter), this could also be explainable as a result of the long-term sexual abuse she had to endure: H. H.'s sexual organs must have been too big to even in some way properly fit with her reproductive system. She probably received incurable damages in the uterus that made a well-going pregnancy impossible.
Fridge Horror:
For some reason, when Charlotte Haze first finds out that the man she married is a pedophile lusting after her daughter, her first instinct is not to get to her daughter immediately, but to sit down and write letters. Worse that one of them was addressed to such pedophile containing such parts as “...oh, my dearest, oh my..." and "after a year of separation we may...”
She might still love Humbert thinking if she got Lola out of the way permanently (with boarding school) she could forgive him and work on him and he would fall in love with herself instead (Or if she didn’t love him she’d get away from him while Lola is at school).
She may also have a hard time explaining Humber's intentions to her daughter. She likely felt guilty and stressed out, she married Humbert and now he was after their daughter. She thought letter writing would help her feel better before she began getting her daughter to safety. But by the time she finished writing everything down she got run over before mailing her letters; before doing anything to save her daughter.
Dolores wasn't going to be a "nymphet" forever. What the hell would've happened if she hadn't managed to escape before she grew up? While there's no indication that H.H. was planning on killing her after she stopped being interesting, he almost certainly wouldn't have just let her leave after everything he did...
Humbert does casually mention at one point that he was thinking about impregnating Lolita when she got older, so that they might be able to have a daughter who would grow up to be a "nymphet" as well... that's not exactly fridge, since it's stated outright, but it's certainly horror.
