Looks like I hit a dead end. O, who I thought would be the 1 person who would understand, didn't seem to. Now I have to decide if I want to stay with her, or peruse what I feel is a better type of relationship, where co-dependency is not so much an issue and features many other benefits. I didn't expect it to go like this with both O and A, since both are bi-curious and both have mentioned a 3-way more than once, but both also consider the idea of a 3rd person as a threat. To me a 3-way is rather cheap, and only for a quick sex thrill, and a 3 person relationship rather beneficial and deeper, although obviously very complicated to start.
A word of advice that I was told once: 2 people can see the same event/idea, 100% totally different, so is best to never assume what someone's interpretation might be.