The singer uploaded a video full of romantic clips of the couple at the beach, including one of Derulo showing love to Frumes' baby bump. It ended with the words "Coming Soon" written in the sand.
"Mom & Dad," Frumes captioned a photo of the pair on her own account.
Derulo and Frumes met at the gym just before the coronavirus pandemic, he said in an interview with People, and they've been enjoying creating TikTok videos together over the past several months.
See their announcement on Derulo's Instagram here, and on Frumes' Instagram here.