Christian Cowan and Sam Smith’s Met Gala Debut as a Couple

Early in their relationship, the fashion designer Christian Cowan gave the Grammy Award-winning singer Sam Smith a metal-plated rose dipped in silver. It was that display of affection that became an inspiration for their looks the Met Gala.

“I wanted to speak to the theme, the night, the tone that Anna loves, but also to our own story,” Mr. Cowan said in a phone interview on Monday.

The pair, who have been rumored to be a couple for some time now, confirmed their relationship of about two years to The New York Times. In their first appearance at the Met Gala as guests, they hard-launched as a couple on the museum steps in matching white and black suits that reflected this year’s “Garden of Time” dress code.

Hours ahead of the festivities, Mr. Cowan, who designed and styled the garments, said he was feeling excited and not at all nervous as relaxed jazz played in his room at the Mark Hotel.

“I’m currently wearing eye patches, and it’s totally dreamy and chill,” he said.

Mr. Cowan, who has designed since he was 18, acknowledged that he is known for his glittery garments. He had no intention of abandoning that inclination, he said, but he wanted to show that he was still a “hard core fashion nerd,” this time through a more classic look that “represents a level of chicness.”

He took tailoring inspiration from Oscar Wilde, nodding to his preference for cravats, strong shoulders, long blazers and straight trousers. “There was an austereness to his suiting, and there was also a romance that I really was drawn to,” he said.

The shiny, metal-dipped red roses — electroplated in 24-karat gold and sterling silver — were affixed to the jackets as a clasp.

The flowers created a minor difficulty in the design process because of the heaviness of the metals. Mr. Cowan said they went through four variations so that the blazer had the right structure to support the weight.

“And it’s a functional closure,” he said. “We can pull it out and pull it in, which I think is fun.”

Smith, who is nonbinary, took a gender neutral approach and included a chiffon skirt that draped over trousers with significant side slits.

Their cravats matched their eye colors — brown for Mr. Cowan and blue for Smith.

Unlike the friction that could come about when dressing a partner, Mr. Cowan said that styling Smith had been a breeze because Smith has worked with major designers and understands the process.

“It was very collaborative, and because we’re partners, I do know Sam,” Mr. Cowan said. “So it’s nice to be able to design something for someone you know intimately.”