Thus, though she must perform a "masculine" role in order to be successful, she must perform it in a "feminine" way, and thus disrupt the idea of gender. This also ties in quite nicely with Cullen's assertion that the modern individual is defined by love and connection with their family, rather than by their place in society. The very fact that meg is the one to save Charles Wallace is a further affirmation of the willingness -- on the part of both Meg and L'Engle -- to buck the societal roles that have been laid out for women and instead to embrace their own identity based on their love for others, and to a greater or lesser degree the love that others bear them. Of course, the romance that is still blossoming between Meg and Calvin still entrenches this novel somewhat...

The suggestion that the romantic love of and for a male figure helps to complete her identity can be read even more cynically, to imply that neither L'Engle nor her heroine have truly been able to escape societal expectations and demands regarding the proper role and identity for women, but it can als be read as an admonition that singularity of perspective and self-enforced isolation are simply inhuman ways of being.
At its heart, being human is exactly what Madeleine L'Engle's A Wrinkle in Time is all about. Meg is finding her place in the world, in her family, and her own sense of identity as an adolescent female, it is true, but more importantly she is finding her place as a person, and recognizing the vast array and presentations of personhood that are possible in the universe. She and the reader both ultimately come to the conclusion that any definition of identity, based on gender or anything else, is necessarily incomplete, and that the intellect holds very few human answers.

Works Cited

Culler, Jonathan. Literary Theory: A Very Short Introduction.

L'Engle, Madeleine. A Wrinkle in Time. New York: Yearling, 1973.