If my bf wanted me to ping him any time I was briefly seeing my gf that would probably get annoying eventually. But if it was something he needed initially, of course I would do it. I mean, how long does it take to send a text message? Poly brings up a lot of difficult emotions, and better that I be very briefly inconvenienced than that he be struggling needlessly. I would assume that over time, as he saw I was respecting his request and that he could trust me and the situation, he could let go of that requirement.
What I wouldn't do is forget he ever asked, especially if he'd reminded me multiple times and it was obviously important to him. Either your fiance has an incredibly shitty memory, he's lying, or he doesn't care enough to try to remember.
You're not overreacting. None of this is ok. I mean...
...if you guys are supposed to spend the rest of your life together and he can't or won't give you the tiniest window into his emotional decisions, and he says he'll do major things (like break up with someone!) but then doesn't with no explanation, and he's stringing multiple other women along and treating them without a modicum of respect, and he won't honor a simple request from you... how is this supposed to work in a way that leaves you happy, healthy, and sane?
What the hell is up with this guy?
The major players. Me, 30ish bi female. Gia, girlfriend of 4+ years. Clay, boyfriend/dom. Davis, ex/friend/"it's complicated." Eddie, roommate & fwb.
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy and Nikki, Clay's partners. Liam, Eddie's husband.