Is it right to marry cousin brother?

In the United States, our kinship system does not have a separate Word to refer to the spouse of a cousin, so on that basis you can argue that someone who marries your cousin is not "related" to you. However, in a sense you *are* related to that person, especially if you have regular or close contact with your cousin and his or her spouse, so you can choose to refer to the spouse as a cousin if you want to create a greater or inclusive sense of family.