Rihanna and A$AP Rocky Not Fighting, Just Exhausted After Long Met Gala Day

Rihanna and A$AP Rocky had fans reading into their post-Met Gala vibe ... but TMZ has learned there's no trouble in the relationship ... just pure exhaustion after a marathon day.

Sources close to the couple tell TMZ ... the two had been going nonstop for nearly 16 hours by the time they were caught on camera leaving the invite-only gala Monday night, bouncing between prep, appearances, and the main event -- leaving them totally drained.

Our sources say the video in question shows nothing more than two people who were wiped out. "It was a long day and they were running on empty," one source tells us.

As we first reported ... RiRi and Rocky were filmed by a photog having what looked like an emotional conversation inside their Sprinter van after the gala, and yeah, at moments, they seemed a little annoyed with each other.

That footage, combined with clips of them looking serious outside -- including viral video showing Rihanna shooting Rocky a look while he chatted with another woman -- had fans thinking there might be tension, but we're told that’s not the case, and there's no issue between them.

Our sources say they're happy, and people are simply overanalyzing a tired moment.