Machine Gun Kelly's celebrating his 33rd trip around the sun ... and while pics from inside his bash look pretty insane, what's most notable is the absence of his fiancée Megan Fox -- further fueling rumors they might be dunzo.
MGK posted some snaps from his birthday party, captioning them "i am 32 + 🖕🏼” ... with a good chunk of his pals in attendance as he blew out the candles -- on a cake with his cat's face on it, no less.
Looked like a pretty epic party ... one that even cops apparently had to shut down, but fans have been pointing out the fact Megan was nowhere to be found -- and as you can imagine, the comments section had its fair share of people asking where she was.
As we reported, Megan had fans convinced they split back in February, when she unfollowed him and scrubbed a lot of their photos together from her social media -- she also quoted lyrics from Beyoncé's "Lemonade" album ... code for dealing with cheating.
She went dark on IG for a bit before coming back, and denying any cheating rumors that pinned MGK with his guitarist, Sophie Lloyd.
TMZ broke the story, the 2 were spotted together earlier this month, however -- hanging out in Hawaii with MF in a new hairdo. Unclear what's going on in that relationship, but we know she wasn't with him for his big day.