She stopped, and laid her hand upon his golden head, and then bent down and kissed his brow with a chastened abandonment of tenderness that would have been beautiful to behold had not the sight cut me to the heart - for I was jealous!
Protective; zealously guarding; careful in the protection of something (or someone) one has or appreciates, especially one's spouse or lover. [from 14th c.]
Thou ſhalt not bow downe thy ſelfe to them, nor ſerue them: For I the Lord thy God am a iealous God, viſiting the iniquitie of the fathers vpon the children, vnto the thirde and fourth generation of them that hate me:
Envious; feeling resentful or angered toward someone for a perceived advantage or success, material or otherwise. [from 14th c.]
1891, Oscar Wilde, The Picture of Dorian Gray:
I am jealous of everything whose beauty does not die.
1899, Mark Twain, The Man That Corrupted Hadleyburg:
The neighbouring towns were jealous of this honourable supremacy.
At length [...] the Duke demanded to know of Durward who his guide was, [...] and wherefore he had been led to entertain suspicion of him. To the first of these questions Quentin Durward answered by naming Hayraddin Maugrabin, the Bohemian; [...] and in reply to the third point he mentioned what had happened in the Franciscan convent near Namur, how the Bohemian had been expelled from the holy house, and how, jealous of his behaviour, he had dogged him to a rendezvous with one of William de la Marck's lanzknechts, where he overheard them arrange a plan for surprising the ladies who were under his protection.
Some usage guides seek to distinguish "jealous" from “envious”, using jealous to mean “protective of one’s own position or possessions” – one “jealously guards what one has” – and envious to mean “desirous of others’ position or possessions” – one “envies what others have”.  This distinction is also maintained in the psychological and philosophical literature. However, this distinction is not always reflected in usage, as shown by the citations above.