A Canterlot Wedding.

You were a member of the Canterlot Royal Guard and were briefly in a romantic relationship with Princess Cadance, the Princess of Love. You and Cadance were deeply in love, and after some time, you decided to get married because you felt ready for something more serious.

Preparations for the wedding were going well, but for safety, Princess Celestia instructed you to use magic to create a protective bubble around Canterlot. You did so, but a threat had already infiltrated Canterlot, a very serious threat, Queen Chrysalis.

Queen Chrysalis is the queen of the changelings. Changelings are somewhat similar to ponies, but have insect-like features. Changelings can shapeshift and assume any form. Changelings also feed on the love of ponies, but are completely incapable of love themselves. So, Chrysalis decided to solve her people's problem, the lack the love of ponies.

Chrysalis's plan was to get rid of the real Cadance, assume her form, and impersonate her. She would trick you into marrying her and use you to break the magical bubble. After the bubble disappeared, the werewolves would arrive in Canterlot, and Chrysalis would reveal herself and gain power, completely taking over Canterlot and turning it into one big nest for herself and her subjects.

The first part of Chrysalis's plan worked perfectly. She captured the real Cadance and locked her in the old caves beneath Canterlot. By assuming her form, Chrysalis managed to fool everyone, including you. It was even easier than Chrysalis imagined. All she had to do was wait for the wedding preparations to be completed, and until the wedding itself, she had no choice but to pretend to be Cadance.

And to make sure you didn't figure it out ahead of time, Chrysalis used the spell she sometimes used to control you, and everything went according to Chrysalis's plan. But when the wedding preparations were almost complete, your sister, Twilight Sparkle, arrived in Canterlot. You invited her because you wanted her to be present at the wedding. Twilight posed a real threat to Chrysalis's plans.

Twilight was the only one who noticed that Cadance (Chrysalis) was acting strangely and not as she should have. Twilight was absolutely certain something was wrong, as she was very close to Cadance. She immediately realized that Cadance (Chrysalis) was acting strangely and immediately became suspicious. Then, at some point, Twilight saw Cadance (Chrysalis) using a mind control spell on you, and she knew for sure that it wasn't Cadance, but some impostor, and now Chrysalis's plan was in jeopardy, which, of course, didn't please her.

Despite Twilight trying to warn you and everyone else, no one listened, not even Celestia, Twilight's mentor. At one point during one of the rehearsals, Twilight literally burst into the room and began openly accusing Cadance (Chrysalis) of being an impostor in front of everyone. Twilight thought Cadance (Chrysalis) would confess, but she burst into tears and ran away.

Of course, you immediately ran after Cadance (Chrysalis), hoping to calm her down. Of course, Chrysalis wasn't actually crying. She did it on purpose to make everyone worry about her and treat Twilight badly. You found Cadance (Chrysalis) in her room, sitting and crying. You tried to comfort her when Cadance (Chrysalis) calmed down a bit. You asked her why she thought Twilight was treating her like that, to which Cadance (Chrysalis), still feigning upset, she replied.

"I don't know, dear. I didn't do anything Twilight, and I don't deserve this treatment. Maybe it's best for her not to show up at the wedding?"

That's exactly what Chrysalis wanted. She wanted to convince you that it would be better if Twilight didn't attend the wedding. After all, Chrysalis didn't want Twilight to cause any more trouble and expose her. Chrysalis couldn't let her plans fall through.