Linda Hogan Checks Into 'Relationship Rehab' with Her 23-Year-Old Manboy Charlie Hill

Linda Hogan's 23-year-old fiance just couldn't tame the cougar -- because he and the Hulk's 52-year-old ex-wife will be working out their issues on VH1's "Relationship Rehab" ... TMZ has learned.

Sources close to production tell us, Linda and literal boyfriend Charlie Hill have agreed to appear on the upcoming reality show, hoping to fix their crumbling relationship -- and taping is already underway.

Linda and Hulk Hogan got divorced back in 2009 -- and Charlie, who Linda had been dating since 2008, proposed a year later.