Muri, I liked how you described all three points of view in the situation. Sounds like you have a very finely-tuned sense of how other people think/feel, and maybe that is part of the problem... you know (or think you know) how boyfriend and A feel before they have really processed it themselves. You are getting ahead of them. And getting ahead of yourself.
Can you try just going with the flow for a little while? especially since A made such a favourable impression on you and seems willing to take things at a pace that is comfortable for you?
Maybe try to just relax and let life unfold a little... without worrying about it. It sounds like these two guys genuinely care about you. Maybe the healthiest thing for you is just to focus on that for now.
good luck to you!
Leelee, all alone.