He has fallen for a girl who is kept on a very short leash. He saw "dulzura en tu sonrisa" [sweetness in your smile], but she is "prisionera... entre paredes sin sol" [a prisoner between walls with no sun], and someone has "puesto cadenas" [put chains] on her freedom. He does not want her to be a "princesa de un cuento de hadas" [fairy-tale princess]; he wants her to be the queen of his real life. Note "Quisiera que fueras" [I wish you were], a nice example of the past subjunctive used for wishing.
The chorus is a sweet, simple request: "Quiero que seas mi estrella para que ilumines siempre nuestro camino al andar" [I want you to be my star so you always light our path as we walk]. In the second verse he even admits "Aventuras las he tenido" [I've had my flings], but promises that with her it is different and that he will not try to change her innocence or her principles. It is a gentle, respectful courtship song, with a hint that her family is the wall he has to get past.