Machine Gun Kelly/instagram
The "Bloody Valentine" singer, 32, uploaded a carousel of images to his Instagram to mark her special day Monday, showing the famous couple in various fun and candid moments.
The first image saw Kelly and Fox on a ride that appeared to be Space Mountain, with the Transformers star sticking her tongue out while making the sign of the horns with one hand.
The second photo showed off the couple's matching ring-finger tattoos, voodoo dolls with pinned hearts and visible stitches.
The picture that followed was presumably of the tattoos' inspiration — two large pink dolls perched on a table with X's and button O's for eyes.
Machine Gun Kelly/instagram
Other images saw Fox meditating, as well as the couple handling an adorable kitten.
"Wishing the happiest birthday to my ethereal light being," Kelly, born Colson Baker, wrote in the caption.
"I love you maki," he continued, adding the emojis for a knife, heart and two candles.
RELATED VIDEO: Machine Gun Kelly Dedicates Emotional BBMAs Performance to 'Wife' Megan Fox and Their 'Unborn Child'
Just ahead of her birthday, Fox created a bit of a stir on her own Instagram, when she shared a slideshow of photos and videos showing her rocking a sparkly blue jumpsuit while in Las Vegas for the 2022 Billboard Music Awards over the weekend.
In the carousel, Fox revealed she had to alter the ensemble to participate in a certain NSFW activity with Kelly. In a screen grab of a text message thread with stylist Maeve Reilly, the Jennifer's Body star asked, "Was this blue outfit expensive because we just cut a hole in the crotch so we could have sex?"
Reilly's response in the text exchange read, "I hate you" followed by a trio of laughing with tears emojis, followed by, "I'll fix it."
Kelly delivered a special performance at the Billboard Music Awards Sunday night, where he hit the stage and dedicated his song "Twin Flame" to Fox. "I wrote this song for my wife," he said, sparking speculation the couple tied the knot.
Near the end of his emotional performance, Kelly took a moment to announce another dedication, saying: "And this is for our unborn child."
"Go to sleep / I'll see you in my dreams / This changes everything / Now I have to set you free," he sang, as the sound of a heartbeat followed shortly after.
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Kelly tweeted about the ballad after the award show, writing that it "broke my heart to sing the end of that song." He added in a second tweet: "I recorded twin flame 2 years ago today, the second half came a year later. beautifully serendipitous getting to sing it for you tonight."
Speaking with Entertainment Tonight on the red carpet of the BBMAs, the star revealed he had played the moving track for Fox when he first wrote it.
"It's like it's all meant to be," he said. Added Fox, who has often referred to her beau as her twin flame: "There's like super special secret meaning to the song as well. So I'm sure I will be [emotional], but I can't cry and f--- up this eyeliner."