Questions of confusion, polyamory, and unicorns
Here's the situation:
I am in a monogamous relationship that has been going on for more than a year. About a month ago, my girlfriend and I realized that our closest mutual friend (female) most likely has romantic interest in me, given our observations about how she has been acting towards me and the ever increasing sexual tension between me and the girl that both me and my girlfriend feel when all three of us are hanging out.
I think that this would be a fairly straight forward situation as these things go, except for one thing. About a week before we started suspecting she had feelings for me, something strange happened. My girlfriend and this girl are very close physically and emotionally. They were both cuddling on my girlfriend's bed (which is normal for them) when the girl started kissing my girlfriend. This took her completely by surprise, because to her knowledge, both of them were completely heterosexual. But it didn't just happen once. They were kissing on and off through the evening. My girlfriend and I were very confused why that happened, and were going to talk to the girl, but didn't know how to approach it. Thankfully what happened didn't change our interactions with her, and we all continued to hang out like normal. Then about a week ago, she kissed my girlfriend again when they were alone.
So now my girlfriend and I are trying to figure out what to do. It has become apparent that both me and my girlfriend need to talk with this girl, but we aren't sure how. It is highly probable that this girl likes me, and it is obvious that she feels something towards my girlfriend (whether this is just sexual, or maybe romantic as well, we have no idea).
My girlfriend is hesitantly open to the idea of a poly relationship (I say hesitantly because a) she has never really considered the idea before, b) she does not yet know how she feels about this girl: they are best friends and very close, so the possibility that romantic feelings on my girlfriend's part exist is there, hampered only by the fact that she has never had romantic feelings for a woman before, and doesn't know if she is capable, and c) she is afraid of losing me).
I have never considered myself poly before, but I find the idea of having a poly relationship with this girl appealing. There has always been romantic potential between her and I, but nothing ever came of it. What I do not want is to leave my girlfriend for this girl. I say there is romantic potential, but I have no concrete feelings at the moment. To be honest, I'm not entirely sure how I feel about her.
If it turns out that this girl does indeed like both of us, and is open to the idea of poly, then we would probably start "dating" this girl to see if our close friendship grew into something more. But it's not like we are actively pursuing the idea of poly. It is one option among many that has been brought up after much deliberation between my girlfriend and I.
The problem right now is that we don't know how to bring all this up. I need to talk to her to figure out if she does have romantic feelings towards me. My girlfriend needs to talk to her to figure out the same thing. Who she has feelings for will determine the next step. And what if she does like both of us? How on earth do I bring up poly without making her feel undervalued, like just another girlfriend (shortchanging her), or sounding like a pervert, or giving her false hope?
This girl is incredibly important to both of us and the last thing we want is to alienate our friendship with her.