Except most (not all, but most) sitcoms seem based around families which are at best, to all intents and purposes, dysfunctional.

The "probably well-meaning, but slobbish, set in his ways and indolent husband" and the "why did someone this smart and good looking settle on THIS chump for a significant other, never mind enable half their crap for them" wife is a staple of too many sitcoms to list.

The only reason these couples are viewed as "happy" is narrative necessity and them repeating it, rather than any visible evidence.