Sebastian Stan Had Extreme Concern For His 'Avengers: Infinity War' Co-Star Tom Hiddleston Dating Taylor Swift

Avengers: Infinity War star Sebastian Stan admits he was "really worried" for Marvel co-star Tom Hiddleston when it was revealed the Loki actor and country-slash-pop star Taylor Swift were an item in 2016.

Asked about his reaction to the news during a visit to Watch What Happens Live with Andy Cohen, Stan said it was "one of awe and extreme concern."

"Obsession and yet, at the same time — I know I want the word," Stan said, laughing. "I don't know, I was really worried — mainly for him."

"You know, love is quick and hard," he added.

Asked if he ever talked about it with Hiddleston, Stan said, "No, I didn't. I actually forgot about that incident."

Hiddleston and Swift were a coupling for about three months in 2016 before officially splitting in September of that year.

The globe-trotting lovers were seen out and about in Los Angeles, New York, and Italy, prompting rumors the high-profile relationship was a stunt.

"The truth is that Taylor Swift and I are together, and we're very happy," Hiddleston told The Hollywood Reporter in July 2016, less than two weeks after the stars were seen celebrating the Fourth of July. "That's the truth. It's not a publicity stunt."

A source speaking to Us Weekly said Swift "put the brakes on the relationship" after the Thor and Avengers star "wanted the relationship to be more public than she was comfortable with."

The sourced added Hiddleston was "embarrassed that the relationship fizzled out."

The 'Look What You Made Me Do' and 'Ready For It' singer followed up her relationship with Hiddleston with another British actor, newcomer Joe Alwyn.

Last February, Hiddleston told GQ magazine Swift is "an amazing woman," saying the superstar singer is "generous and kind and lovely, and we had the best time."

Reaffirming "of course it was real," Hiddleston explained the relationship ended as both were seeking a normal relationship.

"So we decided to go out for dinner, we decided to travel," he said. "She's incredible. [But] a relationship in the limelight...a relationship always takes work. And it's not just the limelight. It's everything else."

Hiddleston and Stan both appear in Avengers: Infinity War, now playing.