Hullo and welcome!
I trust you have brought up the issue of A's sexually ambiguous behavior while intoxicated with her? It might be she doesn't realize it's bothering you or that she fully well realizes and likes to play with it. The threesomes seem to lead to (or be a result of) an unhealthy power balance/struggle in your vee and thus I agree, would be wise to be put on hold until you figure this thing out.
Me: bi female in my twenties