Wow, ChloeJane, that's a tough one!
I can see how you can do a lot of good in your position, and that might be threatened if/when you come out. Then again, being out might cause other kind of good things. And I totally understand your concern for your career. While I really value openness, I find it unlikely that political community would be ready for public polyamory. Bisexuality, maybe, but poly is just so "out there".
I'm a student now, but some of my dreams for future involve a position not unlike yours, so I've been pondering these kinds of things a bit lately. I'm out now, but I'm not sure if that would be feasible in a political workplace (where you're not supposed to advertise your personal life
, and yet it's ok that everybody knows you're married
From what you tell about your position, I think I would not commit to never coming out, but neither would I do it just yet. I would wait until I'm on a REALLY stable basis with the girlfriend, as in, when I would be ready to get married was it allowed by law. At that point I would consider coming out. It's like with public figures in gay/lesbian relationships: they are a "role model", they have to show that same-sex-relatioships are committed and respectable and all that. If you do go public, you can't have a messy (or even a non-messy) break-up with either of your partners without it being held as evidence about poly being non-committed (because monogamous straight couples never break up, right?
). And I guess you might need to commit to polyfidelity, because I'm sure any outside sexual relationships would attract even more unreasonable amounts of scandal-seeking media attention than they do with the straight&monogamous public figures.
Then, I don't know. Somebody who is in your position, and ethically poly, might be able to have a big impact on public perception of polyamory. If they are careful about how and when to come out, but not without a considerable personal risk.