Well, guess I'll just update here as things progress (or don't, however the case may be).
I'm coming down a little from the whole "OMG! Big Conversation!" high from my talk with DF about opening up our relationship. (I'd said "going poly" on the intro thread, but that sounds awfully flippant in my head and I'm not sure how else to put it).
I think the timing of this could have been better somehow. Right now I'm still stuck with my attraction to the other guy (OK, I was trying to avoid borrowing abbreviations, but OG works quite well, so I'm going to use it), and while DF and I have discussed poly, we haven't said "OK we're doing it now!", so I guess DF is just processing things. He still seems gung-ho about it. He keeps mentioning finding a girlfriend, and I think he wants for us both to end up starting our additional relationships around the same time, although we both feel that's a bit unrealistic.
What sort of sucks is that now I'm STILL not sure what to DO with my attraction to OG. I haven't discussed anything with OG since we had the conversation about our mutual, accidental states of arousal last week, and we haven't been in that situation since then (although that could just be because I'm swamped with school and haven't spent much time alone with him since then). We went for coffee last night and met a couple at Starbucks, and mostly just talked and laughed about random crap. I feel like there's less tension between us (or maybe it's mostly on my part) after having told DF about my attraction to OG, which I think is a good thing. So less beating myself up over "how could you go and let yourself get attracted to someone else AGAIN?!" and more "OK, let's just let this be".
I guess I'm in a hurry because I do have this pre-existing attraction to someone, and DF does not, which is unfair. I guess ideally I could have come to the conclusion earlier that I would like to try being open to the possibility of poly relationships, and discussed that with DF BEFORE becoming actually attracted to someone. I guess I don't really start thinking about the possibility of having feelings for more than one person at a time until I am actually in the situation.Years ago I became very attracted to another friend of mine, although it happened quite gradually. I remember wondering if it was possible to love two people at the same time, because it seemed to me like I did. I hadn't really heard anything about polyamory back then, though, so I didn't even know how to start discussing it with DF (then DBF), and besides that, we were a younger, newer couple and didn't have the stronger foundation of communication that we do now.