There are 6 persons including bride and groom. right.
we have to arrange them in a row.
Now you can think , in whatever manner you place them , either the bride would be to the right side of the groom or the left side. Is there other possibility ? No.
so ultimately
way to arrange the bride to the left of groom(WL) + way to arrange bride to the right of groom(WR) = total possible ways to arrange 6 people in a row.
Now you can think that WL and WR are symmetric ,i mean WL=WR
and total number of ways to arrange 6 people in a row = 6!
so ultimately WL= 6! / 2 =>360