Hey Sarah. Thank you for responding; I appreciate it. I thought I should clarify a few things, though.
It's true, we never talked about how often to contact one another. In the beginning we'd text every day, and slowly dwindled to once every couple of days. That was still going on up until the two weeks happened. I did approach him about it, cautiously. I didn't want to be confrontational because we never talked about it. But I did ask him what was up with that. His answer amounted to he simply didn't. He said he thought about it a few times, but just didn't reach out. There was nothing super stressful or pressing in his work or personal life; he just didn't text me. In comparison he revealed to me he's never gone more than three days without talking to the partner of his he's moving in with. Therefore, even though we technically talked about what happened, I still harbor some anger and upset.
As for moving in with that partner, I know it doesn't necessarily mean he's "choosing" her over me or any of his other partners. He's said to me flat out he would be happy to live with the partner he's moving in with (let's just call her G), his other partner (H), and "maybe" me. He and G are not in dire financial straights, there's nothing stressful happening; it's simply that their leases are up at that time and they've decided to move in together. I try not to compare myself to G, but I feel he compares her to me. He has said (warning: sexual content ahead)
He's also said he likes his partners loud and outgoing (G is very extroverted) and I am not. So yes, I feel compared to his other partners a lot.
Not to be a Debbie Downer, but I do want to touch on the omission thing. He did omit at least some of us. In addition to G and H he is dating me and another person. At the very least he omitted the other person, which means he probably omitted me, too. Even if he didn't omit me, and I'm sorry to be a stickler here, but there is no excuse to misgender me or anyone he's dating (I'm not the only trans person he's dating), especially when we've been seeing each other for almost five months. It's not even about "categories." He didn't have to specify he was dating women; if he was really concerned about gender and seem neutral about it, he could have said people.
I agree with you that he and I probably need to discuss all of this. But I do believe this goes beyond a simple situation of poor communication. I'm going to try to find the best way to approach it, but I still do feel very much conflicted. I do hope this new information I am sharing might also shed more light on the situation, or at the very least give someone more to go off of. Thank you, again, for your response. I'm glad to count you as a friend.