I was taught that good comedy usually begins in chaos and ends in order (the reverse being the case in tragedy). For Shakespeare, who was probably a Catholic, order would mean everything traditional, including marriage.

The universality of the institution of marriage makes it an excellent topic for drama in general.

The modern "comedy" is what Shakespeare would have called a "farce".

It used to be that a "tragedy" ended in a sad state.  A "comedy" ended in a happy state.  The farce was simply designed to evoke laughter throughout.

I've noticed that the very few "comedies" I've seen in the last few years are all, as Mithrandylan noted above, oriented towards the obscene.  I shutter to think that I actually thought they were "funny" in my youth.  If any of them are "oriented to Marriage" is not something I can answer, though it would make sense since marriage is a universally understood institution as MariaCatherine pointed out, which is also the reason marriage is under so great an attack today:  Attack under the pretense of "tragedy" as well as though "farce".  In fact, the traditional understanding of marriage is today also often being attacked in "comedy", or happy endings.