When you think happiness, I hope you think that little black dress.

After Taylor Swift stepped out for an NYC date night with Travis Kelce in December wearing Fleur du Mal’s Long Sleeve Flared Corset Dress, the turtleneck LBD almost immediately sold out.

But as of Wednesday, the style’s been restocked and is now available to shop in sizes XS through L in both black and heather gray.

With its soft and stretchy jacquard fabrication, corset seaming and feminine flared skirt, it’s the perfect piece to pair with tall boots and statement outerwear while it’s still freezing outside — like the crystal-embellished Simkhai Gianni Coat Swift selected — and wear solo with heels once it warms up.

For those hoping to complete the look in Swift-approved style, the Bonbonwhims Heart Gumdrop Tennis Necklace the Grammy winner paired with her dress is currently available for preorder in several colors.

Swift often opts for classic LBDs while out and about; over the past year, she’s also worn versions from Balmain, Simkhai, Alaïa and Alice + Olivia, making her Fleur du Mal fit-and-flare among the more accessibly priced options in her closet.

And as brand CEO Jennifer Zuccarini recently told The Post, Fleur du Mal doesn’t pay celebrities to wear its pieces.

“To pay any of those people to wear something would be astronomical,” she said, adding, “I think about everything through that lens of who our Fleur woman is and what she might be interested in.”

In addition to Swift — who also incorporated Fleur du Mal looks into her “Lover” and “You Need to Calm Down” music video — the label’s dressed stars including Sabrina Carpenter, Lupita Nyong’o and Halsey. Its silk slip dresses have also appeared onscreen on Nicole Kidman in “Babygirl” and Anya Taylor-Joy in “The Menu.”

This article was written by Elana Fishman, founding editor of Page Six Style. Elana applies her celebrity fashion and beauty expertise to shoppable content for fellow fans as the host of video series including Style Trial, Heart to Cart and Beauty Scoop — and by tracking down every Taylor Swift-worn style so you can shop it, too. Elana consults celebrity stylists on the latest street style and red carpet trends, researches which celebrity-backed brands and products are worth it, and chats with the stars themselves for beauty and fashion recommendations. Prior to Page Six Style’s inception in 2018, Elana covered celebrity fashion at Vox Media, Lucky, Marie Claire and Teen Vogue.