180 degree rule

[Mark Baird]

you can use dissolves to lessen the impact of crossing the line. A nice LOOOOG dissolve with the bride on the right facing left and the bride on the left facing right with pleanty of screen space to super the two images at once can look really nice.

If you are cutting it like dialogue or movie action then worry about the line. If it is soft disolves with a flowing, almost musical feel, then the line is much less important.