Sweethearts! How 17 couples transformed from their prom pics to their wedding pics.

Sydnie Haag shared her and her husband's prom-to-wedding pics, starting a trend.

Talk about high school sweethearts!

"I was looking back at old photos and thinking how different my husband looked and how young we looked," Hagg said. "I posted it on Twitter and didn't think much of it."

To her surprise, however, she woke up the next day to her phone going crazy with notifications of others on social media following suit.

Although it was a shock, Haag sees this trend as a positive thing. She enjoys viewing other couples' photos.

"It made me feel happy because I'm the type of person that likes looking at pictures and looking at people's stories," Haag said. "It's nice to see where people started and see where they ended up."

However, Haag doesn't like to post everything on social media. She thinks that some things are important to keep to oneself. Her advice regarding social media and relationships is to understand your limits when posting and to remember that the whole world doesn't need to know what's going on behind the scenes.

Check out these other adorable high school-to-newlywed photos: