Make your escape.
If possible, you and the beloved should leave the party separately. Coordinating an underhand, SEAL Team Six-style exit isn’t going to be easy after a half dozen Moscow Mules, but anything you can do to hoodwink prying coworkers is a win. Nothing sets miserable people off quite like others getting laid, and office buildings are veritable warehouses of despair. In other words, don’t give the damaged buzzards in middle management or specialized buzzkills from HR anything to hold against you.