The split attraction model or SAM is a model of attraction used by many ace-spec and aro-spec people to describe their identity. The SAM states that for some people sexual attraction and romantic attraction are two different things. For explain, an asexual person may feel romantic attraction, and an aromantic person may feel sexual attraction. In those cases the a-spec person may describe their identity using the SAM.
If someone's sexual and romantic orientation are the same they can use one word. For example, one would not have to say 'pansexual and panromantic' they could just say they're pansexual.
There are several ways to express their split attraction. If someone is aromantic but still feels sexual attraction toward people of the same gender they could identify and 'aromantic and homosexual'. They could also identify as 'aromantic and gay/lesbian'. Either way the a-spec person identifies both their romantic and sexual orientation.
History
The first recorded instance of a model of orientation taking into account split attraction was in 1879, by Karl Heinrich Ulrichs, a German writer, who published 12 books on non-heterosexual attraction. In those books Ulrichs came up with various classifications of orientations which are fairly similar to modern LGB+ identities. Amount his works he described people who are ' konjunktiver and disjunktiver' or 'conjunctive and disjunctive bisexuality'[1]. The first is described as one who has both 'tender' and 'passionate' feelings for both men and women. The second is one who has 'tender' feelings for men, but 'passionate' feelings for women (if the person was a man- the reverse if they were a woman). However, Ulrichs' model never caught on due to the complexity.
The next instance of separating sexual and romantic attraction was in 1979 by the psychologist Dorothy Tennov. With the publication of her book 'Love and Limerence: The Experience of Being in Love'[2]. In the book Tennov described 'limerence' a form of attraction which could be described as a crush, or an infatuation with someone. Although Tennov viewed sex as being a part of limerence she acknowledged that it was not the main focus of it.
The first hints of what would become the modern SAM began with 'affectional attraction/orientation' which was coined at some point in the 1980's. It's unclear when the term was first used. Coining for the terms as often attributed to Curt Pavola, a gay rights activist from Washington, and to Lisa Diamond, a psychologist. However, there are instances of the phrase that predate both of these individuals.
Around 2001 there was a push for a way to classify asexuals. One of the earliest instances to still is the ABCD classification system on AVEN[3], which recognizes that some asexuals may feel romantic attraction. Around the same time there was a Yahoo e-mail group known as 'Haven For The Human Amoeba'[4], where in 2001 there was discussions of term 'hetero-asexual'. It wasn't until 2005 that the modern form of the SAM was created on AVEN. By 2007 the terminology was widely used in asexual circles.