Eyewitnesses tell TMZ ... MGK and Megan were having dinner at the Four Seasons Hotel on the Big Island Monday night, enjoying each other's company -- but there was no kissing or touching going on, which is a rare sight for them.
We're told they dined for about an hour, and even waved to some of his fans as the 2 headed out for the night. They followed up their meal with a walk down to the beach.
BTW, don't let that red hair fool ya -- that's for sure M.F. ... she dyed it last month.
Of course, people took that as a sign they split ... some even speculating he had a fling with his band's guitarist, Sophie Lloyd -- whose team fully denied all of it.
Megan then came back to Instagram, shutting down rumors ..."There has been no third party interference in this relationship of any kind. That includes but is not limited to...actual humans, DMs, AI bots or succubus demons."