What if my mistress now (Thomas Morley)

What if my mistress now will needs unconstant be?
Wilt thou be then so false in love as well as she?
No, no, such falsehood flee, though women faithless be.

My mistress frowns, and swears that now I love her not,
The change she finds is that which my despair begot,
Despair which is my love, since she all faith forgot.

She blames my truth and causelessly accuseth me;
I must not let mine eyes report what they do see;
My thoughts restrain'd must be, and yet fast will go free.

If she doth change, she must not be in constancy;
For why she doth profess to take such liberty;
Herself she will untie, and yet fast bound am I.

If she at once do please to favour more than one
I agreed in humble sort to make my moan;
I spake not to a stone, where sense of love is none.

But now let love in time redress all these my wrongs;
And let my love receive the due to her belongs,
Else thus I'll frame my song or change my mistress' longs.

Which if I find my heart some otherwhere to dwell,
For, loving, not to be belov'd, it is a hell.
Since so my hap befell, I bid my love farewell.