Short Answer: No.
Answer from the United States Conference of Catholic Bishops:
"Denial of marriage -- Since cohabitation is not in itself a canonical impediment to marriage, the couple may not be refused marriage solely on the basis of cohabitation. Marriage preparation may continue even if the couple refuses to separate. Pastoral ministers can be assured that to assist couples in regularizing their situation is not to approve of cohabitation."
Source: Marriage Preparation and Cohabiting Couples: An Information Report on New Realities and Pastoral Practices