re: "Palimony"
It was Lee Marvin, and his partner Michelle - the case went on the dockets as Marvin v Marvin. Suits of that type brought since have become known as "Marvin actions".
Thing is, it had nothing to do with "common law marriage", which is only recognized in one form or another in 15 states plus DC. There's more about that at Common Law Marriage Fact Sheet.
Specific to case law coming out of Marvin:
The term "palimony" implicitly analogizes the rights of a nonmarital partner to the right of a spouse to receive alimony. However, a Marvin action is in no way analogous to an action for dissolution of marriage.
The [California] Supreme Court in Marvin expressly declined to treat unmarried cohabitants like married persons, overruling two prior decisions of the Court of Appeal which had applied the Family Law Act to unmarried cohabitants. Id. at 681. Since Marvin, California courts have been scrupulous in separating Marvin actions from domestic relations actions. The courts have held:
-- Trial courts in divorce proceedings do not have jurisdiction over Marvin claims arising out of premarital cohabitation. In re Marriage of Johnson (1983) 143 Cal.App.3d 57 [191 Cal.Rptr. 545]. (A Marvin claim filed in a civil action may, however, be consolidated with a dissolution proceeding. Id.)
-- An award of spousal support may not be based on the parties' cohabitation before marriage. In re Marriage of Bukaty (1986) 180 Cal.App.3d 143 [225 Cal.Rptr. 492].
-- A Marvin case may not be processed in the superior court under the special family law rules. Schafer v. Superior Court (1986) 180 Cal.App.3d 305 [225 Cal.Rptr. 513].
-- Jurisdiction standards applicable to domestic relations cases do not apply to Marvin actions. Kroopf v. Guffey (1986) 183 Cal.App.3d 1351, 1357-1358 [228 Cal.Rptr. 807].
-- The obligation to pay support pursuant to a stipulated judgment in a Marvin action is -- unlike an order for spousal support -- dischargeable in bankruptcy. In re James P. Doyle (9th Cir. BAP 1986) 70 B.R. 106.
-- A former unmarried partner is not entitled to an award of pendente lite support. Friedman v. Friedman 20 Cal.App.4th 876 (1993).
Accordingly, the term "palimony" is inaccurate insofar as it implicitly compares a "pal's" rights with the rights of a divorcing spouse. A spouse's right to receive alimony and to share in marital property is based on his or her status as a spouse. A "pal" does not have any comparable automatic right to property or support based only on his or her status as a nonmarital partner. Rather, a Marvin plaintiff must prove some other underlying basis for his or her claim, such as an express or implied contract.
The source for that is California "Palimony" Law -- An Overview.
I haven't been able to find a convenient list of which states recognize palimony as actionable. Passing through the first three pages of the Google search, I found three that expressly do not - New York, Massachusetts, and Michigan - and one other that does: New Jersey.
In cases where judges order support for an unmarried partner, they have found that one partner promised to support the other partner in return for being taken care of while they lived together. In all reported cases so far, support has been provided by a male partner to a female partner. Courts have treated these situations as if the parties had a contract, not like marriage, where the right to support is based on an obligation between the partners. Under the law, the duty to support one another still belongs only to spouses in a legal marriage.
There was a time when living together in a long-term relationship and acting as husband and wife was considered under the law to be equal to marriage. That was called common law marriage, which was abolished by statute in New Jersey in 1939. Since common law marriage ended, there are no longer any laws with guidelines for determining whether support should be awarded from one unmarried partner to another when their long-term relationship ends.
Source - Palimony - Support for Unmarried Partners Who Live Together Reading further on that page will show that, unlike CA, NJ has decided to process "palimony" cases in Family Court, but still treats it as "breach of contract".
The point is: until the wrangling over semantics is settled (and it will be, to great wailing and wringing of conservatively religious hands), the recourse to "palimony" isn't available in every state; is non-uniformly administered among states that recognize it; is adjudicated as contract law, not marriage/divorce a.k.a. "family" law; and probably isn't worth pursuing without there being big buck$ involved.