Harry Styles and Zoë Kravitz Not Exclusive, Just Hooking Up

The internet may've lost its mind over Harry Styles and Zoë Kravitz getting together ... but the stars are keeping it cool and casual, TMZ has learned.

Sources familiar with the situation tell TMZ ... the singer and the actress are merely hooking up -- defining their relationship as a "friends with benefits" type arrangement.

We're told the A-listers don't consider their relationship as a serious one ... focusing on keeping it fun for now. They're just hanging out!!!

Sources say HS and ZK haven't even put a label on this situationship, as they're not exclusive in any way. So, don't expect Zoë to bring Harry as a plus one to Taylor Swift's wedding to Travis Kelce ... at least, not yet, anyway. It's early days, folks.

Remember, it was just last week that the pair sent fans into a tizzy with a cozy outing in Rome, Italy. The One Direction alum and the 'Batman' star were arm in arm as they took in the Eternal City.

While Zoë flew solo to the NYC premiere of her new movie, "Caught Stealing," last week, she and Harry linked up days later ... holding hands while hitting the streets for a day date.