Long story short, my family has been looking into some family history and we suspect that one of my great-great grandmothers might have had an affair and (possibly?) a lovechild which she passed off as her legitimate child. The child in question was born in 1889 when the mother was mid-40s... she had two older children previously born in the 1870s. The child was supposedly considered the black sheep of the family and eventually he actually committed suicide in the late 1920s. He left behind two daughters who believed their dad was possibly a lovechild. This is a long story, lots of family rumors, not a whole lot of details.
How likely would it be for a married Victorian woman to keep a love child and pass that child off as her legitimate offspring? Are there any examples of a Victorian woman having an affair, passing the child off as her as her legal husband’s? Also, is there anyway we can dig deeper into this sort of thing beyond birth records, diaries, rumors, etc?
To explain the difficulty you are likely to have in digging deeper into the possibility of a married woman having given birth to a "lovechild" in 1889 I will provide some background into the legal status of the child. In the United States of America, laws about illegitimacy were state based, but varied very little and that variation mainly over what marriages were legitimate e.g. In some states, first cousins could marry and in some they couldn't. The laws derived from British laws and were closely aligned.
If a woman was legitimately married and gave birth to a child during the marriage (birth occurred after the date of marriage or within nine months after cessation of the marriage through either death of the husband or divorce) then the strong legal assumption was that the child was the legitimate offspring of both the husband and the wife.
The legitimacy of the child could only be legally challenged by someone with standing to do so and in most jurisdictions the only person with such standing was the husband. The burden of proof lay on the person claiming illegitimacy.
"Where the child is born of a married woman, every presumption is in favor of its legitimacy. In order to establish the paternity of a person other than the husband, there must be affirmative evidence from which it can reasonably be inferred that the husband had not had access to the wife during the time when the child was begotten, or else evidence that the husband was impotent. Moreover, neither the husband, nor the wife is allowed to prove'non-access; and the dying declarations of the wife to that effect are inadmissible. The wife may, however, testify to the illicit intercourse with the third party."
So it was very difficult for a child born in wedlock to be proved illegitimate. It was not sufficient for the husband to prove that his wife had an affair with someone else, or to simply claim that he had not had sex with his wife during the relevant period even if his wife admitted both those things. He had to prove to the Court's satisfaction that he could not have possibly fathered the child either because he was impotent or absent.
So unless her husband had been away during the relevant period it would be both likely and easy for her to pass that child off as her husband's. Legally the child would be her husband's. Birth records would name the child as her husband's. Unless you can find some record of a dispute between husband and wife over the child, gossip and rumors are the best you are likely to get and they wouldn't prove that the child was a 'lovechild' only that people thought he might be.
An example of how state laws applied can be found here: 1917 Law of Pennsylvania Relating to Illegitimacy: W.Logan McCoy: Journal of Criminal Law and Criminology