A gene that doesn’t propagate the species?
I wonder how THAT ONE evolved!
What would be the effect of a gene that causes anyone (male or female) who possesses it to be extremely strongly attracted to females? I would posit that even if such a gene might be detrimental to the reproductive success of any female carriers, it might conceivably double the rate of reproductive success among male carriers. If it did so, it could be expected to be passed on through succeeding generations. Likewise a gene which causes carriers to be attracted to males might harm the success of male carriers, but boost the success rate for female carriers. Again, a gene which did so could be passed on through succeeding generations.
If one considers it likely that sexual attraction is not controlled by a single gene, but by many, one should expect that many individuals would not have a perfectly-balanced set of sexual-attraction genes, but many would have a set that is biased in varying degrees toward males or toward females.