Even though fans have always wanted the co-stars to be a thing in real life, they are not.
But they do share an amazing relationship that isn't romantically oriented.
Balfe and Heughan are great friends in real life. Their friendship didn't start off amazing, though.
When the pair first met for the show, things were less than comfortable. Heughan, during an interview, said that both of them were "a little shy and nervous" at first.
He also talked about how the proposition of Balfe being his "telly wife" for the next five to six years was a little unsettling at the onset.
Balfe, however, said elsewhere that their chemistry, in a sense, developed pretty quickly. That was because he "put her at ease" swiftly.
She also has a fondness for him. When asked what her favorite things about him were, she gushed, "Sam's just so kind. He's a really good friend. He always checks in."
She also opined that he had the biggest heart and a small ego.
"I feel very lucky. Sam and I have an amazing bond, we're really great friends," she added.
Playing her character alongside Heughan, and the show in general, also made her more romantic in real life.
Heughan, too, has similar feelings about his co-star.
He admitted to Pop Sugar that they get on very well and he was lucky to have someone so talented and nice as his friend.
The actor even missed Balfe when they did not get to shoot scenes together. "[It] is kind of like losing someone in your family. A loved one. It's very strange, and I don't enjoy it." he said.
He always looked forward to working with her.
Balfe even affected his life (in a good way). As she was, according to him, a "social animal," she forced him to socialize and always welcomed him into her world.
She even came to his defense when gay rumors about him were going around on the internet.
