The UAE has no way to reliably check most of its visitors' marital status. Last names being different means close to nothing -- increasingly so in OECD countries and historically more generally in Muslim-majority countries where it has not been general tradition to change family name at time of religious marriage.

Religious marriages are not invalid in the UAE even if the visitors' home states deny they are valid. So what document is the UAE going to check for marital status? Nothing reliable or necessary, and it's no problem unless you make a bad scene or step on the wrong national's toe.