This can be won in the Himmelstein Sniper assassin level by ruining the wedding by doing the following:
-Most importantly, kill the father of the bride undetected before he can walk her down the aisle.
-Shoot the bride's bouquet
-Shoot the lighting at the photo op
-Shoot the Band's instruments: the violin, microphone, and knock down the top of the piano
-Shoot the wedding cake
-Shoot the Priest's wine glass
-Shoot the dove cage
If you do all of these things before the bride and groom reach the relevant events, then you will get the achievement immediately.
Edit: I'm getting multiple reports that killing the father of the bride is NOT necessary for this achievement. For myself though, the achievement wouldn't pop until I did. Please take both my solution and this edit with a grain of salt, as I am unsure of the truth.
(Credit to Bastiaen)