The Succession actor, 47, recently admitted that it strikes a nerve "a little bit" seeing Hawes, 45, be intimate with her costar Richard Madden in the series, which premiered on BBC One in 2018. "It's just weird," he told The Times.
"You can get quite close to the actors you're working with and all that stuff. It's odd," added Macfadyen, who met Hawes on the set of their BBC One show Spooks in 2002.
As a fellow actor, Macfadyen said he understands that filming a sex scene is "the least sexy thing you can possibly imagine."
Hawes starred in Bodyguard as home secretary, the Rt Hon Julia Montague MP, who develops a relationship with her war veteran bodyguard David Budd (Madden) despite their differing views. The show became known for its steamy sex scenes.
Madden, 35, previously told PEOPLE that a potential second season of the show could be in the cards. "It's definitely a possibility," he said in December 2018. "I'm meeting Jed [Mercurio] the writer tomorrow, actually. I think we'll probably have a glass of champagne and do some talking."
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Hawes tied the knot with Macfadyen in November 2004. The couple shares two children, daughter Maggie, 16, and son Ralph, 15, and Macfadyen is stepdad to Hawes' first son Myles, 21, from her previous marriage to Spencer McCallum.
Macfadyen can currently be seen playing Tom Wambsgans in HBO's Succession, which was renewed for season 4 last month.