Sorry, we're here continuing a discussion that was started a year ago, you're out of the loop and just haven't seen that I've addressed this before.
I'm not asking to change anything, just add a couple of lines - Mizz acknowledging that he is not offering an exclusive relationship to Rael and he's messing around with someone else would be fine(other characters give you a fair warning, there's no reason why Mizz shouldn't).
The problem isn't that Mizz is polyamorous/polygamous/whatever, the problem is that not mentioning that little fact while coming on to Rael comes off as manipulative and insincere, which was not author's intent, as far as I can tell.
They are just being intentionally dense about how poorly that part had turned out, readily accepting praise, but ignoring criticism. I like their writing, but I'm massively disappointed in them as a person.