If a person has serious reason to believe they're not actually married to the person they're living with, I don't think doing nothing is an option. They need to either ask the Church to regularize their situation or seek the declaration of annulment.
With so much chaos in the Church, a woman can ask 10 different priest/bishops and get 10 different answers.
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Rome rubber stamps all annulment requests.
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I don't think either if those are good options.
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Some women in these circuмstances choose to stay. Some women choose to leave. It is whatever God calls them to do and we can't fault either choice. God knows her heart.
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