You might check out the original Free Love movement in the United States. In the 19th century, when women like Victoria Woodhull spoke of Free Love initially, they didn't simply mean men and women having sex with each other without the sanction of the State & the Church. They also meant women saying 'no' without encountering pressures from lovers to say 'yes.' They were most often opposed to abortion as well. So, even before the advent of 2nd-wave feminism, the gay liberation front, radicalesbians, the queer nation, etc., 'free love' meant liberating women from not only the sorts of oppressions Engels wrote of but also from the ways in which different-sex love + sexuality were organized, _under the circumstances not of their own making_ (hence their emphasis on saying no and opposition to abortion). Both the first Free Love movement and the 60s sex lib were much more complicated than your posts allow. (See _Intimate Matters: A History of Sexuality in America_ for more info on this. If you don't have enough time, read at least "Part III. Toward a New Sexual Order, 1880-1930.")
When our contemporary critics use the term heterosexism, the word is not meant to stigmatize those who are heterosexually inclined having sex with members of the so-called opposite sex. On the contrary, without social pressures to adopt the vaguely defined but nonetheless implicitly present and sometimes violently enforced heterosexual norms (which refer to not only sexual acts + fantasies but also how you talk, how you walk, etc., since gender norms have been tightly wound up with norms of sexuality), sex life of all--whatever preference, disposition, etc. one might have--would most likely improve.
Just as the abolition of racism would liberate many from 'whiteness,' the abolition of pressures to become heterosexual would liberate not only 'same-sex' love & sex but also 'different-sex' love & sex from the material/ideological repressions that must be reproduced to create and maintain separate sexual identities.
There is no reason why one's chromosome, choice of dress, demeanor, sexual object choice (in what you actually do, what you dream about but don't get to do, what you fear but also find fascinating, etc.), 'lifestyle' (the word that many pejoratively use but Foucault thought of as potentially liberating and at least promising), etc. should neatly line up along the developmental lines plotted by the very limited range of normal scripts of heterosexual romance.
get laid & stay laid-back,
Yoshie