Genders are all correct. It may help to mention that the three of us are very young, they are college freshman and I am a year behind them. A and I were each other's first relationship and M had only been in one before.
A and M had been close friends for years before, and while they were interested in each other, they were much slower coming together than M and I were, and never seemed as romantic. It was closer in execution to a vee, but technically we were all involved with each other.
Yes, although I think that I could have handled being monogamous with M if it were anyone but A.
A and I dated for 10 months before we even learned what polayamory was, and we felt like it would suit us, especially with how close we already were with M. M joined us around our 11 month anniversary.
A's decision to leave was, to me, a huge surprise. I hadn't noticed anything terribly wrong in our relationship, which was also pretty much the cause. I gave A and M different levels of attention, favoring M. A tried to tell me without saying "Hey, give me more attention!", that sort of directness not being in his nature, but getting hints is not in mine and I didn't see how much he needed our dynamics to change. His first attempt to break up resulted in a "break", where M and I were to treat him as just a friend. I was under the impression that if I fixed some arbitrary list of things wrong, that he would return, but after two weeks he decided he didn't have any romantic feelings for us at all and the break up became "official".
A and I talked very little after then. We tried to be "just friends" for about a week and I couldn't handle it.
M stepped up and tried to be my everything. We didn't think A would change his mind (as much as I wished he would) so we tried to comfort each other with words of exclusivity. That M and I would learn to be happy with just each other and without A. It worked for M but never really seemed to work for me.
I know I need to talk to A much more than the little bit we've done. He's not even sure of his feelings, and here I am stressed that I'm going to have to make some horrible decision between them when I might not even be given (or have to make) that choice.
Thank you so very much, just explaining things to you is helping me sort through what I'm feeling and what's really going on.