Nicole wrote an interesting blog about relationships and committment. It got me thinking about being single. It's been nearly 6 years since I was "out there" but I relate to the frustration at wanting something more and running up against the wall of "maybe".
The thing is, I think you have to simply live your truth, whether it's monogamy or playing the field. Relationships aren't scientific, don't follow logic and can't be run in a sort of "playing chicken" fashion - first to blink, loses or conversely first to blink, wins. If you're the kind of person who, when you care for someone deeply, wants to concentrate on that one person, great. If you're the kind of person who, when you care for someone deeply, still wants to leave yourself open to other options, great -- as long as the other person is aware of your particular need and agrees to the arrangement.
The trouble starts when you aren't on the same page of the "rule book".
Be who you are, live according to your own needs and your truth and you will attract someone else who feels the same truth.