She should be a supporting role not a lead because she isn’t physically attractive enough.
She works well in Sideways because she’s a supporting role and the love interest of Paul Giamatti’s character who is also unattractive.
Every time there’s a scene in Killing Eve with Sandra Oh which is half of each episode, I’m rolling my eyes and want it to be over. While the scenes with the other lead actress is more interesting.
It’s cringe that the lead assassin character is attracted to Sandra Oh’s character. It’s unbelievable.
And Sandra Oh’s husband in the show is too attractive to be married to her.
This week on “This actress fails to make my dick hard and therefore should not be on my TV” we have this stellar example. If someone would like to move this to the Pit, I’m sure I could find more to say on the subject.
I’m going to go out on a limb here and assume the OP doesn’t find it unrealistic when a physically unattractive male lead has a romantic partner who is beautiful.