He's singing about how the woman he loved and lost has many moods and shades to her personality; if anything, that demonstrates that he sees her as a real, three-dimensional person. Not sexist in the least.
How is this song sexist? Listen to that line 'please don't let on that you knew me when...'that line is full of self doubt. It's like he's feeling the same emotions as the girl, but he's able to approach it from a more philosophical and understanding perspective. Consider Dylan's own quotes when he says that unless he actually lived the situation, the lyrics could never be true to him, so let's assume that he lived this situation and was able to get so much out of it. This song has everything: love, beauty, anger, condescension, regret, self doubt, fear and ultimately an understanding, albeit a bit of an arrogant understanding. But that's how relationships are, I guess it's really how you interpret the way he says baby...is it from an affectionate or condescending perspective?
Even if he was differentiating on gender, what's wrong with writing a love song about women, given they are the subject of his life's romances? He's hardly going to write something in that sense about men, if he's never been romantically involved with one.
Not everything that highlights gender (particularly from an individual's subjective position) is sexist. Lighten up ffs.