Marxism teaches us how to change the world, not how to live our lives. If you try to adopt Marxism as a way of life, then that's what it becomes - a lifestyle option rather than politics, and you end up in a sect or a cult indistinguishable from any other small, cranky, incestuous social circle. And I use the word "incestuous" advisedly. The sexcapades of small Marxist or anarchist social circles are legendary.
You do hear about otherwise upstanding socialist groups which have an internal culture based on primitive chimp-like sexual hierarchy, where rank has its privileges, and one of those privileges is sexual access to the desirable gender(s). On a lower level, you get small-group drama like you get in any community who tends to look to itself for its romantic partners. I really think that socialists should bring back the ancestral tribal tradition of (cultural or totemic) exogamy - or, to put it in modern language, don't screw the crew.
And the really dodgy thing is when people make apparent appeals to political principles - such as the critique of the nuclear family - to justify treating their comrades, friends and lovers with disrespect. There is a difference between free love (which socialists have been historically for, and with good reason) and irresponsible sex (which is what I think so many of us actually practice). Two-facedness and using other people are not socialist virtues. I do hear that Fripp's Guitar Craft tradition has actual community guidelines for how to sex one another responsibly while on their courses, although apparently the advice for those who're just beginning the recommended practice is "keep it in your pants". Good advice.
Robert Anton Wilson was wrong, the freedom to fuck is not the keystone to all other freedoms - in fact, that very idea (that the only real freedom is the freedom of private leisure-time activity) is at the basis of bourgeois individualism. I value my freedom to fuck or not to fuck, but I value my right to my own labour and my right to democratic participation equally as high.