Henri III having seen her at Rheims, during his temporary residence in that city, became enamoured of her person, and their marriage took place on the 5th of February 1575.

Francois de Luxembourg, of the House of Brienne, had for some time paid his addresses to Mademoiselle de Lorraine, with the hope and intention of making her his wife; a fact which the licentious and frivolous King no sooner ascertained than he declared his inclination to effect an alliance between the disappointed suitor and his own mistress, Mademoiselle de Chateauneuf, for whom he was anxious to provide through this medium.

He consequently proposed the arrangement to M.de Luxembourg on the day of his coronation, but received the cold and firm reply that the Count felt himself bound to congratulate Mademoiselle de Lorraine on her good fortune, since by changing her lover she had also been enabled to increase her dignity; but that, as regarded himself, since he could derive no benefit whatever from becoming the husband of Mademoiselle de Chateauneuf, he begged that his Majesty would excuse him from contracting such an alliance.

The King, however, declared that he would admit of no refusal, and insisted upon his instant obedience; whereupon M.de Luxembourg demanded eight days to make the necessary preparations, to which Henry demurred, and it was finally arranged that he should be allowed three days for that purpose, after which he was to hold himself prepared to obey the royal command.
These three days sufficed to enable the intended victim to make his escape, and he accordingly left the kingdom.

His sarcasm against herself had so deeply irritated Queen Louise that after the death of her husband she entreated Henri IV to revenge her injured dignity upon her former suitor, but the monarch declined to aid in any further persecution of the unfortunate young noble.