Since Washington Irving is a writer from the Romantic period, the reader must not ignore the more subtle aspects of conflict in this humorous satire.  For, along with his humorous inflated diction, in "Rip van Winkle" Irving conveys a nostalgia for the "tranquility" of the colonial period as he satirizes his contemporary post-Revolutionary society that, like Mrs. van Winkle--the "daring tongue of this terrible virago--is too dogmatic and argumentative:

The very character of people seemed changed.  There was a busy, bustling disputatious tone about it, instead of the accustomed phlegm and drowsy tranquility.

Here was a general shout burst from the by standers--'A tory!' a Tory! a spy! a Refugee!  hustle him! away with him!'....

Rip's heart died away at hearing of these sad changes in his home and friends, and finding himself thus alone in the world.

Perhaps, then, the real protagonist is Washington Irving in the character of Rip van Winkle and the antagonist is the post-Revolutionary society with its "disputatious" and disturbing nature.

In my opinion, the protagonist and antagonist in this story are the Van Winkles.  Rip is the protagonist and his wife is the antagonist.

We are clearly meant to sympathize and identify with Rip van Winkle.  He is presented as a basically good guy, though a bit flawed.  Even though we are not told that his wife is a bad person, she definitely comes off as the mean one.

In the story, she is the one who is constantly foiling Rip -- not letting him do what he wants.  Even after 20 years, when he wakes up and she is dead, his life is largely defined by her absence.