A classic to check out would be the writings of Voltairine de Cleyre (http://www.theanarchistlibrary.org/authors/Voltairine_de_Cleyre.html),
especially "They Who Marry Do Ill". I think Goldman may also have written on the topic of "free love." Certainly she practiced it in her life.
A contemporary anarchist who writes on these topics is Jaime Heckert (http://www.theanarchistlibrary.org/authors/Jamie_Heckert.html
There is so much anarchist writing on non-monogamous love/romance/intimacy/sex/etc. I don't even know where to tell you to look first.
The main point I've considered when thinking about my previous experience in romantic relationships (all human relationships, really) is the clash of expectations between involved parties. Different expectations can often manifest themselves in patriarchal ways ("What do you mean you're not going to cook me dinner?") They can also be less easily categorizable. I'm a pretty verbally-oriented person, so I always want to make sure that my hopes/expectations are clear to my partner ("I'm not looking for anything serious right now.") and vice versa. A lot of people's expectations are culturally-originated. As anarchists generally are people who are intentionally trying to know and express their individual desires in spite of what this culture expects, our expectations are even less likely to conform to cultural mandates (whether that might be monogamy, celibacy or hooking up) than others. Thus, I think it behooves us to be quite explicit and clear about our desires. That is, of course, assuming we can be quite sure what it is we really want!
Scarcity is (or should be) a controversial concept to anarchists. A lot of the content of that concept is capitalist rubbish, however there is /something/ useful there, I believe. Certainly much of what draws me to specific individuals is their utter uniqueness. As the TCI quote alludes, most of what passes for romance in this culture is hollow ritual or a commodity experience informed by the likes of Cosmo magazine. Rare are the people that are liberated from these massifying tendencies.