There is no such thing as "reverse" discrimination. Discrimination is discrimination, whether the victim is, for example, Black or white, female or male, gay or straight. When the employee claiming discrimination is in the majority, however, in the 6th Circuit they must not only show disparate treatment, but also must show "background circumstances to support the suspicion that the defendant is that unusual employer who discriminates against the majority."
Which brings us to the story of Marlean Ames, a straight woman who sued the Ohio Department of Youth Services for sex discrimination under Title VII claiming that her lesbian supervisor discriminated against her because of her sexual orientation. Ames claimed that OHYS passed her over for a promotion, demoted her, and promoted a gay man to her former position.