"Woman falsey accused ex boyfriend of rape following consensual sex to keep her current ex boyfriend from breaking up with her"
The above incident fits in the category that Prof. Eugene Kanin's landmark study of false rape claims identified as the most common motive for false rape claims -- it served the woman's "need to provide a plausible explanation" for a sexual encounter with a male acquaintance. In other words, an alibi.
Here, the young woman had consensual sex with her ex-boyfriend and then feared that if her current boyfriend found out, he would break up with her. So she claimed the ex raped her.
Consider how ruthless this young woman is: she was willing to sacrifice her ex-boyfriend to a felony prison term -- and destroy his life forever -- to insure her current boyfriend would not discover her unfaithfulness.
See: The False Rape Society | Source | July 20, 2008
Also Professor Eugene's Kanin's landmark study which begins:-
With the cooperation of the police agency of a small metropolitan community, 45 consecutive, disposed, false rape allegations covering a 9 year period were studied. These false rape allegations constitute 41% the total forcible rape cases (n = 109) reported during this period.
These false allegations appear to serve three major functions for the complainants: providing an alibi, seeking revenge, and obtaining sympathy and attention. False rape allegations are not the consequence of a gender-linked aberration, as frequently claimed, but reflect impulsive and desperate efforts to cope with personal and social stress situations.