Theories on the disappearance of Chuck Cunningham

Do folks remember how in the original Happy Days (regardless of whether you count the one where Harold Gould was Howard Cunningham or Tom Bosley) the Cunninghams had three kids? Charles, Richard and Joan?
   Chuck went off to college and was never seen from again, so by the time Joanie married Chachi, Howard’s wedding speech spoke of how he had raised two kids.
   Long-time Happy Days watchers like me were going, ‘Howie, three kids! Where’s Chuck?’ At least explain his fate in that final episode! After all, even Richie came back for it so both Ron Howard and Ted McGinley were there together.
   Twenty-three years later, I figured out why he might not have been mentioned by Howard. Remember, this was pre-Civil Rights 1960s (the 1950s having finished by the end of the 1979 season). (a) Chuck was gay and disowned. (b) Chuck married an African American woman and was disowned. (c) Chuck met a dude called Charles Manson.
   Now you know.