The song is from season 2 episode 26 of MLP:FiM.
♫ Lyrics for the song:
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[Twilight Sparkle]

Love is in bloom
A beautiful bride, a handsome groom,
Two hearts becoming one
A bond that cannot be undone because

Love is in bloom
A beautiful bride, a handsome groom
I said love is in bloom
You're starting a life and making room
For us (For us, For us....)


[Twilight Sparkle] [background]

Love is in bloom
A beautiful bride, a handsome groom
I said love is in bloom
You're starting a life and making room
For us, (For us... For us...Aah...)