The Royal Wedding of Equestrian Royal Guard Captain Shining Armor (Twilight Sparkle's brother) and Princess Cadence (Princess Celestia's niece) was almost ruined by the appearance of the Changeling Queen Chrysalis for the season 2 finale.
One of the wonderful songs sung by both Queen Chrysalis (posing as princess Cadence) and the real Princess Cadence (when Twilight Sparkle discovers her brother is being brainwashed by Chrysalis's spell and confronts her about it) is This Day (Known as This Day Aria.
Here are the lyrics:
Chrysalis:
This Day is going to be Perfect.
The kind of day of which I've dreamed since I was small.
Everypony will gather 'round
Say I look lovely in my gown
What they don't know is that I have fooled them all...
***
Cadence:
This day was going to be perfect
The kind of day of which I've dreamed since I was small.
But instead of having cake
with all my friends to celebrate
My wedding bells, they may not ring for me at all.
***
Chrysalis
I could care less
about the dress
I won't partake
in any cake
Vows? Well I'll be lying when I say
That through any kind of weather
I'll want us to be together
The truth is I don't care for him at all.
No, I do not love the groom.
In my heart, there is no room.
But I still want him to be all mine.
***
Cadence
We must escape before it's too late
Find a way to save the day!
Hope? I'd be lying if I say
That I don't fear that I may lose him
To one who wants to use him
Not care for, love, and cherish him each day.
For I oh so love the groom.
All my thoughts, he does consume.
Oh Shining Armor, I'll be there very soon!
*Music*
***
Chrysalis
Finally the moment has arrived
For me to be one lucky bride
***
Cadence
Oh, the wedding we won't make!
He'll end up marrying a fake!
Shining Armor will be-
***
Chrysalis
Mine! All mine!