The main conflict in the book is that between staying eternally a carefree child and accepting the growth and responsibilities of adulthood. Peter represents the eternal child. He actively resists growing up and wants to live in Neverland, engaged in endless adventures with the Lost Boys. He craves the kind of nurturance or mothering that Wendy provides, but he doesn't want to step up to the plate himself and assume similarly "fatherly" responsibilities. After all, that wouldn't be much fun.

Wendy, who is willing to accept the mantle of adulthood, is Peter's opposite. Both are depicted as good characters (the pirates are their evil contrasts) who choose different paths in life. A central dilemma emerges: while the magical and highly imaginative world of childhood is appealing, it is also a world of stasis and repetition. Peter, albeit with more variation, is living the repeated loop life of the main character in the movie Groundhog Day. It may be delightful for Peter, but he experiences no change and growth. Wendy opts for adulthood, which involves responsibility, aging, loss of imagination, and pain, but she is also fully experiencing all the stages of life.

There are a few conflicts going on in the book. I would say that the main conflict is the man vs. self conflict that surrounds Peter.  Peter desperately wants to avoid growing up.  To Peter, being an eternal child sounds great.  He has few responsibilities outside of having fun.  The conflict for Peter is what to do when Wendy invites him and the Lost Boys back home.  On one hand, he wants to be around Wendy and the boys, but on the other hand he does not want to grow up.  Leaving Never Land will guarantee that he grows up.  In the end, Peter Pan chooses to stay forever young in Never Land.  That sounds nice, but Peter is also forever alone. 

Other conflicts in the story are between Peter and Hook and Hook and the Indians.

What is the conflict in the movie Peter Pan?

One of the central conflicts in the 2003 film of Barrie's work Peter Pan is the challenges Peter undergoes in terms of accepting the responsibility of growing old.  Peter finds himself clinging and demanding to live in his world of make believe, refusing to "grow up."  In such a position, the conflict in inevitable for when feelings develop between he and Wendy, Peter demands such emotions to be seen as "pretend."

The conflict present here is one between individual vs. individual, as Wendy refuses to have her feelings deemed as "make believe."  Throughout the work, Wendy has assumed the responsibility thrust upon her in Neverland as a maternal figure, who takes cares of others and tells stories.  Yet, while Wendy ascends to the demands of maturation, Peter seems to not be willing to accept these conditions.  It is evident that Peter has emotions towards Wendy that indicate his maturation, or "growing up."  Love and emotional commitment are signs of one "growing up" and Peter feels this, yet refuses to accept them as he does not want to have any particular inkling of emotion which indicates that he is growing old.  Hence, another conflict is present, only this time it resides within the individual.