Dakota Mortensen got some unexpected news from cops the night of girlfriend Taylor Frankie Paul’s 2023 arrest ... and his reaction is recorded on body cam video obtained by TMZ.

In the police footage, an officer tells Dakota his "The Secret Lives of Mormon Wives" star girlfriend is not allowed to reach out or make contact with him until a judge hears the case ... after she got cuffed and taken to the local Utah station for alleged domestic violence.

Dakota seems shaken as the reality sets in, peppering cops with questions about next steps while trying to understand what it means for their relationship ... especially with a trip he and Taylor had planned before things suddenly went south.

At one point, Dakota brings up an upcoming Hawaii getaway -- clearly worried the no-contact situation could blow it up -- as his tone seems to shift from confusion to concern as he processes how serious things have gotten.

Cops explain the restriction is temporary, but the uncertainty clearly rattles Dakota ... who’s left dealing with both the legal fallout and a relationship suddenly put on pause.

As we’ve reported, Taylor was taken into custody that night and later pled guilty in abeyance to a felony charge of aggravated assault -- receiving three years of probation that ends this August as part of the plea deal.

We broke the story, her anticipated season of "The Bachelorette" was yanked by the network after ABC saw the footage we obtained showing TFP and Dakota's altercation that fateful night.