Answer:
Wait a minute, why should Wendy give up her life, her dreams, to stay with Peter and never grow up? If they are such a perfect couple, shouldn't he have to meet her half-way?
Explanation:
Yes, to love someone you have to let them be who they are, but can you love them as they need to be loved if you feel that you have to give up yourself to love them? It seems like perhaps by allowing Peter to stay and remain a little boy forever, by not pressuring him into returning with her and growing up, which is what we can pretty clearly see that Wendy wants to do - she wants love and marriage and motherhood from the very beginning of the story, she is loving him the best way she can. She is letting him go and living her life as completely as she can.
By letting Wendy go back to the mundane world and grow up while Peter remains in his fairyland, forever a child, Barrie is perhaps showing us that self and love transcend such things. People are who they are, whether it means they become responsible adults or remain forever child-like and that it is possible for them to respect and love each other, despite their differences. Perhaps they will never be able to be lovers, but perhaps that is not what they need from one another. Perhaps what they need is the love and understanding of a friend who never forgets them, even when everyone else does.
