Could you please explain me the difference between work AT smth and work ON smth?
And what the difference between these two sentences?
You have to work AT a marriage
You have to work ON a marriage
to work at - at home, at the computer, at night
to work on (something, a project and so on) - try to fix something
In your examples, I would say:
You have to work on your marriage (i.e. try to make it work.)