Do wife have the right to reject sex with husband

Yes. The woman can refuse any time or every time. She has free will. When a husband forces his wife to have sex against her will it's called rape. Criminal Sexual Conduct, 2nd degree. 1st degree if the woman suffers lasting physical or mental trauma from it. Marriage is not a free pass for sex on demand. That's not my opinion. It's the law.

I should add that I know this because I served as the foreman on a jury that heard such a case.

WHAT country do you live in... I understand under Islamic law she doesn't. Under Western law she does however. So its important to know where you live, few laws are universal.

BUT its legitimate grounds for a divorce as well if she does.

Good point. My answer was in context of US law. I don't know the laws of other countries. In the USA, woman may refuse sex at any time for any reason.

Based on the OP's user name... I'm guessing a possible far east or middle east residence or at least origion. And we do get users from from very unexpected places.

Let's ask that question: In what legal jurisdiction do you live? Country, state, province, etc?

I don't think that the legal jurisdiction has anything to do with it. Regardless of where you are you can refuse sex. It is the right of any woman, anywhere.

The issues come on the dynamics of the marriage. In some relationships you can refuse and your husband can ignore your declination and take what he wants. Others will allow either side to refuse. Both scenarios will occur in the USA or Iran/Iraq for example.

Up bringing and religious background do play a role. If faith is an important part of your life then discuss it with your rabbi, priest, imam, or head of your local place of worship.

If faith doesn't play a role then talk to your husband and explain why you're refusing sex. If it is a legitimate reason then I am sure he will understand.

An endnote. Don't use sex for power games in your marriage. It is toxic and your marriage will collapse around you. Don't trade sex for favours, money, or possessions. It will devalue the entire act and the meaning behind it. Instead of it being an acting and expression of love and feelings it will become a business transaction.

Does that answer your question?