No, but . . .
A fiancee is nothing more than a potentiality. The couple is “engaged” to be married, but not yet married, not yet husband and wife, and so they have no legally recognizable status that is any different from people who are not engaged to be married.
But if by “fiance” you mean the woman with whom you’ve living for the past three or more years and/or with whom you have had a child or two, then you are, in a sense, a family, even if your marriage was not solemnized (“solemnized” means in this sense a formal marriage ceremony recognized by law). You have some rights as parents, but not as spouses. Because the relationship has not been formally entered into between you and the other member of the couple and without being recorded and recognized by the government, you are still not considered a “family” in the sense that a formally married couple is.
Cohabiting couples (with or without children), however, can in some states have their un-solemnized relationship recognized after the fact as a marriage if the state recognizes common law marriage. Common law may be established by meeting certain legal requirements such as declaring the intent to be regarded as married and cohabiting, rather than as a result of obtaining an official license and engaging in a formal ceremony.
In Utah, an un-solemnized relationship can be recognized as a marriage, if the factors of the statute are met. That statute is:
Utah Code § 30-1-4.5. Validity of marriage not solemnized.
(1) A marriage which is not solemnized according to this chapter shall be legal and valid if a court or administrative order establishes that it arises out of a contract between a man and a woman who:
(a) are of legal age and capable of giving consent;
(b) are legally capable of entering a solemnized marriage under the provisions of this chapter;
(c) have cohabited;
(d) mutually assume marital rights, duties, and obligations; and
(e) who hold themselves out as and have acquired a uniform and general reputation as husband and wife.
(2) The determination or establishment of a marriage under this section shall occur during the relationship described in Subsection (1), or within one year following the termination of that relationship. Evidence of a marriage recognizable under this section may be manifested in any form, and may be proved under the same general rules of evidence as facts in other cases.
Utah Family Law, LC | divorceutah.com | 801-466-9277
https://www.quora.com/Is-a-fiancee-considered-family-by-law/answer/Eric-Johnson-311