What is the poet saying in Sir Thomas Wyatt's sonnet "Divers doth use"?
There is an excellent analysis of this poem on the enotes site (see below). I'm adding a little to gbeaty's answer and also posing a (tentative and untried) alternative reading of the rhyming couplet at the end.
The poet is speaking about different men's attitudes toward infidelity, and is saying that it simply is what it is--no sense crying or carrying on.
This is a sonnet, so the first octave (8 lines) sets up the argument or the situation. Here, as Gbeatty says, he speaks of how so many men cry and wail and carry on when they find out their women are unfaithful.
In the final sestet, a change in direction appears with the word "but" ("but as for me..."). The persona says that he will not wail, lament, be sad, or call her names if his woman changes her mind and he falls from her favour. Instead, he will consider it a natural event, and will "think it is of kind/ That often change doth please a woman's mind"
I haven't read enough of Wyatt to know if he's playing with the meaning of the words "of kind", and I don't have access to an OED from here to find out if both meanings existed when he wrote this, but when I first read this, I thought he was playing with the idea that 1/ it's natural for women to cheat and 2/ it's a kindness that they do. The first reading is definitely the traditional one, and the one I'd use if I had to write, say, an AP lit exam or something like that. The second reading would shift the meaning of the poem somewhat, because it would suggest that he would benefit (consider it a kindness) that women are so changeable (the implication being that if a woman changes her affections 1/ he won't have to live with her forever and 2/ another woman could change her love for another to a love for him; either way, he's be able to see more women). So fun!
A good question, given both the round about delivery and the archaic vocabulary!
If we uncoil those two things, we see him saying something a little sad. He says that many men complain when women change, complain and become spiteful. The men blame the women when their affections change, and love turns to hate. The speaker, though, says he won't complain at all…because that's just the way women are. They're fickle.