Many people have discussed, in various formats, the issue of partner quantity. 

There are a wide variety of opinions, but the debate is most often distilled into a duality of monogamy and polyamory.

Admittedly, both sides of the debate are valid as personal choices, and even ethical -- if expressed honestly and prudently with one's recipient of love. That is to say, if one chooses monogamy for one's self, one does not render a relationship monogamous merely by being monogamous by one's self. No personal choice nullifies the free agent status of another individual. One might object and argue that one can choose to impose their will on another. By making that argument, however, one ignores the plain fact that the "choice" to impose on another is an interpersonal choice by definition. By the same token, a choice to be polyamorous is valid and even ethical if one is honestly polyamorous; that is to say it's not cheating if your recipients are aware of your desire for variety, and you're not putting them at any undesired risk (you are practicing safe sex, for example).

However, this post is not merely intended to justify the validity of both polyamory and monogamy, but to demystify the intense individualism that can be expressed by the choice to be monogamous in particular dimensions of life, so it's more subjective than most of my posts here, admittedly.

Love means different things to different people, but to a Suicrat, the implicit suffix of the phrase. "I love you" is "as a free agent". Suicrats value not people as people (as Objectivists do), nor as the values (materially and otherwise) they obtain from them (which is what some critics seem to think Objectivists do), but as remarkable examples of the beauty that can emerge when one examines a lifetime's culmination of choices, and attempts to extrapolate a trend I'd refer to as "living". (This is not to say I'm promoting some po-mo, life-is-artifice bullshit.)

When a Suicrat says "I love you and only you in this particular way", (s)he acknowledges that the receiver's projected trend is so pleasing to him/her that (s)he feels a unique compulsion to share him or herself in ways (s)he wouldn't otherwise with other people, even other people (s)he cares about, deeply.
 
Now, monogamy does not merely refer to one's attitude towards sexual encounters. In fact, one can be 'monogamous' (which is to say one can express a unique type of love to only one person) in many dimensions other than sex, and be sexually polyamorous; so as you can see the two attitudes of polyamory and monogamy aren't mutually exclusive, as the dualists argue. For example, if one only shares one's hopes, desires, and fears with one other person, but expresses their sexuality with multiple people, they are both monogamous and polyamorous, but in separate dimensions of living. By that same token, if one posts their innermost thoughts on the internet, and shares them with a video game forum, but refuses to engage in sexual activity with any but one person, that person is both polyamorous and monogamous, again in separate dimensions.
 
The attachment of the two terms 'polyamory' and 'monogamy' are justifiably attached to sex by most people, but really, we all love different people in different ways for different reasons. We can't honestly expect to be wholly one or wholly the other, there are too many different people with too many different values to share with us, after all!