Ah, young love.

The 23-year-old Playboy heir Cooper Hefner is engaged to Harry Potter actress Scarlet Byrne!

The bride-to-be took to Instagram to share a photo of her excitement and GORGEOUS rock! Well done, young Hef.

"I was lucky enough to fall in love with my best friend. ?" the Harry Potter alumn wrote of her engagement.

Congrats to the happy couple! Scroll through the gallery to see more Hollywood couples announce the big news on social media.