The blowup between Megan Fox and Machine Gun Kelly may have been the oldest modern source of conflict -- DM's.
Megan found DM's and text messages on MGK's phone that led her to believe he was having an affair ... according to the New York Post.
No word on what the DM's or texts said or who was on the other end, but it was reportedly. enough for Megan to go ballistic.
As we reported, Megan posted lyrics from Beyonce's "Pray You Catch Me," obliquely referencing Jay-Z's alleged cheating ... "You can taste the dishonesty it's all over your breath."
She also unfollowed everyone, save 3 -- Timothee Chalamet, Harry Styles, and Eminem, who has major beef with MGK ... speaking of ... all pics of MGK were deleted from Megan's Insta.
Thing is ... as quickly as it seemed to end between the engaged couple, they tried picking up the pieces. On Valentine's Day, they were at an office building together for 2 hours -- the building has a bunch of therapists' offices, so it all seems to align.
The next day they were seen together in the same car, and apparently were at MGK's home.
So, maybe back together?