Taylor Zakhar Perez being a gem when he is representing the importance of the movie & the book (Red,White & Royal Blue) , Taylor Zakhar Perez once said;
Henry brought Alex to Paris where he wishes he could live as a writer if he were an anonymous person in the world...
Henry wants to make love to Alex right there because it's his 'ideal world' fantasy where he is free to be whoever he wants to be and Alex just belongs there as his lover.