By PEOPLE.COM/Karen Mizoguchi, Sharon Kanter
Updated Dec 24, 2018 @ 3:01 pm

Heidi Klum is a bride-to-be!

The supermodel, 45, announced her engagement to boyfriend Tom Kaulitz on Instagram and Twitter Monday. “I SAID YES,” Klum captioned a black-and-white portrait of her and Kaulitz, 29, as she showed off her new engagement ring.

A source recently told PEOPLE Klum is “so in love” with Kaulitz.

Klum — mom to daughters Lou, 9, and Leni, 14, and sons Johan, 12, and Henry, 13 — and the Tokio Hotel musician first sparked dating rumors back in March after they were spotted kissing on set while she was filming America’s Got Talent. They made their first public appearance as a couple in May for the Cannes amfAR Gala.

RELATED: Heidi Klum on the Downside of Dating Someone 17 Years Younger

Klum’s happy news comes three months after she shut down engagement rumors after she was spotted wearing a huge diamond ring on her left finger at the Emmy Awards.

“I don’t know why everyone keeps saying that. Everyone is asking me. When you do what I do, you wear a lot of fashion. A lot of jewelry. I always look for something that goes with the outfit. So, I wear big rings,” the America’s Got Talent judge told PEOPLE in September.

Klum also said, “there is nothing more to it than that,” though she called Kaulitz “absolutely wonderful.”

This article originally appeared on People. For more stories like this, visit people.com.