I just started reading your blog last night, and wanted to wait until I was finished until I commented. I'm not clear on if Chimpmunk has her own room? I really get the feeling she doesn't. To me it seems like many of the issues are from you not having your own space anymore. From being forced to share a bed with somebody you want to date, but are not dating. Spending most of your social time out as a triad, or as BFFs, when you aren't the first and still too raw over it to be the latter. I can't even imagine coming home from work and not being able to go in my own bedroom because I want to be considerate. In my case I'd probably knock on the door and say I'm home, and then let them come out whenever they were done, but if I didn't I'd be getting increasingly frustrated (and getting mad at myself for not acting) the longer I waited patiently, and I think in your case, this might be why you ended up mad at Airyn?
It seems like the three of you are seriously deep in each others pockets, reading through what you have to say, it sounds like each of you could use some more private time in your dyads, Chimpmunk make herself scarce a couple nights a week (regularly scheduled), you and Airyn make a couple nights a week scheduled where Chipmunk isn't joining you in that day or in bed at all, even to sleep. You getting the bedroom to yourself at least one night while Airyn and Chipmunk are elsewhere. All this togetherness just seems suffocating, and it seems to be taking a big toll on you. Of course you haven't really stated this, so I may just be projecting, but I wonder if because you had one boundary and it was broken, you just gave up trying to have any others for yourself?
So if she doesn't have her own space, Id suggest you get her to be friends with the sofa sometimes, and first decide in your head what you want to do about housing, make up your mind, THEN have that discussion with Airyn about if you're all moving into a bigger place, or if you want your house back just to yourself and Airyn or to move to a bigger place with just Airyn (and I'd factor in the fact that you want to date too at some point here, and so to me the third option would be what I'd go for) where you had an extra bedroom where just him and Chipmunk could be, or for you and your gf (or hopefully someday bf?) to use, so both you and Airyn still have a private bedroom for just you two to retreat to and sleep in.
Ok, thank you for writing your story, I hope blogging is helping put your thoughts in order!
Happiness will never come to those who fail to appreciate what they already have.