Christ the Bridegroom is the central figure in the parable of the ten Virgins (Matthew 25: 1-13); Christ is the divine Bridegroom of the Church as described in the Book of Isaiah (chapter 54), as well as the primary image of Bridegroom Matins. The title is suggestive of his divine presence and watchfulness (“Behold the Bridegroom comes in the middle of the night…”) during Holy Week and his selfless love for his Bride, the Church.
The Bridegroom is also the name given to the central icon used in Bridegroom Matins. The Bridegroom icon and service is also commonly known in the Greek tradition as O Nymphios.

Resource: http://orthodoxwiki.org/Nymphios