Why is giles concerned about his wife in The Crucible?

In the play "The Crucible" by Arthur Miller, Giles Corey is concerned about his wife, Martha Corey, because she has been accused of witchcraft. Giles knows that the accusations are false and is worried that she will be found guilty and executed. He tries to defend her by speaking out against the accusations, but he is also aware that he is putting himself in danger by doing so.