Millie Bobby Brown and Jake Bongiovi are holding on to what they've got.

The Stranger Things actress and the son of Jon Bon Jovi—who announced their engagement in April—recently celebrated another milestone together: his 21st birthday.

On May 7, Millie penned a sweet message to her leading man, sharing it on Instagram alongside a series of photos with Jake. "this sums us up. In bliss, exploring together," she captioned the pictures, including a shot of them at the Enola Holmes 2 premiere in October. "I am eternally holding your hand. happy birthday fiancé. I love you."