Sheree's boyfriend, Tyrone Gilliams, tells TMZ ... he was released from prison in Kentucky last week and ever since then he's been spending lots of QT with Sheree. We're told they've mostly been spending time in Philly ... going out and enjoying cheesesteaks, naturally.

We're told Sheree's helping him acclimate back into life on the outside ... which includes helping him catch up with the latest technology.

True 'RHOA' fans know Tyrone and Sheree dated briefly nearly a decade ago, but he cut off contact when he realized the feds were going to indict him in a wire fraud case. Tyrone was ultimately sentenced to 10 years back in October 2013.

They reconnected around her birthday in 2016, and decided to start dating again -- which meant communicating as much as possible, and Sheree visited him in prison.

Things went south, though, in 2018 when Tyrone says he lost an appeal ... so they stopped dating.

Now that Sheree's single and he's scored an early release -- due to COVID spreading in prison -- he says the time was right to rekindle that old flame.