OP, this is on you.
How?! How is this entirely on me? I've been straight forward with what I am looking for the entire time. I've communicated my level of investment consistently. When she's done things that seem romantic, I've asked about her intentions to make sure I'm not reading things wrong, but she tells me every time that everything is casual.
She IS asking you what you want, you just have romantic ideals about how she should talk.
She is not asking what I want (asking me "Why isn't this working?" or "What's wrong with me?" is not the same as asking me what turns me on) and whenever I try to talk to her about what I want or show her what I want, she clams up because it's "awkward." Talking about the best way to perform oral sex on me should not be awkward. Asking her to use her hands on me should not be awkward. I have no "romantic ideals" about how I want her to respond: she's simply not responding! I want for her to be able to talk about this stuff intellectually and non-romantically, but I'd settle for just any conversation from her after I bring the topic up.
Don't be so sure that you are a "recovering" serial monogamist.
I definitely tend to approach things from a romantic's standpoint, but I'm actively trying to change that and it's part of the reason I've been having such a hard time letting this go. It's the whole reason for the post, honestly: I think I knew deep down that this was a no go, but I was staying with it out of a sense of guilt/commitment/not wanting to be a dick. That's not healthy and folks here have helped me realize it.
Why not give a dating relationship a try with Amanda?
Because I don't want a relationship right now. Like, at all. My last relationship left me totally drained and when I looked back on it, I realized I was vastly unsatisfied in a number of ways. The whole raison d'etre of this casual period of my life is to figure out what I need relationship-wise before I get into another one. To figure out how I can communicate my needs and wants better to my partners. I'm 31-years-old and I don't want to keep having shitty two-year relationships every three years for the rest of my life.
If I did want a relationship, it wouldn't be with her. While she's nice and we enjoy hanging out together, we're clearly not on the same page sex-wise (which is the reason my last relationship failed), she says one thing but does another, and she has trouble communicating about anything sexual. What about any of that is appealing long term?
More time, practice, and quiet affectionate discussions might very well get you what you want in terms of both a physical and emotional relationship.
The whole point to something casual is that neither party has to commit significant time, energy, or affection to the relationship. Literally the whole point. I'm not looking to be a teacher or coach or to bring her out of her shell: that would require a major commitment that I'm not willing or able to make at this point.
My question was: Has this casual relationship run it's course? Your response was: date her forever
Thanks, anyway, for your response.