Architects or advertising executives. Sometimes lead male is one and lead female is the other.

I think it was one of the writers on Cracked that opined it’s because those are the only jobs screenwriters partially understand. They’re people who pitch ideas to customers, kind of like screenwriters do with scripts. So you get a lot of main characters that have a weirdly large amount of down time, a looming deadline to present an idea for an ad campaign or building to your boss and the three executives your boss is kissing up to. Is it the moment of triumph for our main character, has our main character had a change of heart that he can’t run a greenwashing campaign for ExxonMobile anymore because hippy dippy love interest got to him, and now his previous life is going to fall apart and he’s going to start over as a shop owner in a small town or something…