Love's Fitfulness

You say that I am fitful. Sweet, 'tis true;
But 'tis that I your fitfulness obey.
If you are April, how can I be May,
Or flaunt bright roses when you wear sad rue?
Shine like the sun, and my sky will be blue;
Sing, and the lark shall envy me my lay:
I do but follow where you point the way,
And what I feel you doing, straight must do.
The wind might just as well reproach the vane,
As you upbraid me for my shiftings, dear:
Blow from the south, and south I shall remain;
If you keep fixed, be sure I shall not veer.
Nay, on your change my changes so depend,
If ends your love, why then my love must end.