Mama June broke up with her longtime boyfriend, Geno Doak, because she got sober and was over their former lifestyle, and he didn't deal with it well at all ... TMZ has learned.
According to sources close to the former couple ... June called it quits with Geno because they couldn't get on the same page when it came to sobriety -- she was clean, but he was drinking a lot.
Then she began seeing someone else. Our sources say Geno felt like June pulled the rug out from under him and took the breakup very hard. We're told he went to a dark place, which led to him being hospitalized earlier this month in Florida ... before heading to a rehab facility in South Carolina.
As we reported ... June revealed she was done with Geno in mid-August.
His current rehab stint is, obviously, a step in the right direction -- but Geno's legal issues aren't over.