Boundaries. At work you’re coworkers, not dating. Do not bring your dating relationship into the work place.
Be realistic going into it. Know there’s a likelihood you’ll have to manage hurt/hard feelings if it ends. That’s part of why you keep the work relationship separate. You can use that as a natural way of being at work, even if it ends.
What you can’t do it play out shit at work, if you’re together or not. Keep. It. Separate. Have this conservation and agreement beforehand.