It's not the *exact* plot you described, but it's very close. Here's why:
* Airborne virus: The film features a highly contagious virus that devastates Los Angeles.
* Quarantine: The main character, Robert Neville, believes himself to be the last human survivor and has been living in isolation for some time.
* Wife returns: Neville's wife, Anna, does not return from work in the film, but he is desperately seeking other survivors, and he does encounter a mysterious woman who he initially fears is infected.
While the film doesn't have the exact scenario you described, it captures the same themes of isolation, fear, and the desperate struggle for survival in a post-apocalyptic world.