According to Jewish law, for a get to be valid it should not be issued as a result of coercion.
The couple separated four years ago but, embroiled in a custody battle, he has refused to grant her a "get", leaving her in the unenviable position of being a "chained wife", unable to move on and remarry.
The case has gained prominence in the US because Mr Friedman is an aide to Michigan Republican Congressman Dave Camp. Earlier this year his wife's supporters launched a social media campaign to encourage Mr Camp to take action on the matter, but to no avail.
"Withholding a get is considered domestic abuse," said the organisers of this weekend's rallies. "Please convince Aharon Friedman to unchain her.
"Aharon is dependent on the support of these family members. We are confident that Aharon would give a get if they stopped defending his refusal to do so."