Upvote:1
The Catholic church holds that the parties to a marriage must freely consent to it.
1625 The parties to a marriage covenant are a baptized man and woman, free to contract marriage, who freely express their consent; "to be free" means:
not being under constraint;
not impeded by any natural or ecclesiastical law.
1626 The Church holds the exchange of consent between the spouses to be the indispensable element that "makes the marriage." If consent is lacking there is no marriage.
Much more specific detail follows.
So any marriage that is forced on one of the parties, either the widow or the husband's brother in the example, is invalid. A marriage such as described that is entered into freely by both parties is valid.
I'm fairly certain that the Anglican church takes the same view.