Affairs can be powerful detonators. They can invigorate a marriage that's flat, jolt people out of years of complacency. Fear of loss rekindles desire, makes people have conversations they haven't had in years, takes them out of their contrived illusion of safety.
I just want to keep working, really. I just want to keep acting. Playing one part for a very long time builds up in you a desire to play as many different things as you can.