Having to shoot the main portraits after dark is nothing to panic about, there is always light available somewhere, like here outside part of the venue. Matthew has then added in some OCF to isolate the couple from the background and then created another element with some light details from their wedding in possibly another two layers? He might have done this in camera or in post but either way, the result is a picture packed full of drama and romance on an epic scale... It could be a movie poster. Winter weddings might be more stressful because of the weather and the logistics but not because you don't have creative opportunities. Good luck if you still have weddings to shoot.