I mean, I think it's less sexist in it's messaging, and more that MC has some internalized sexism due to a complex he has towards his gender. The story isn't trying to say that one gender is bad, and that their relationship works because "whoops turns out we were wrong" but is trying to show us how he's been holding himself back due to his own ideas and self-deprecation.
after all "and it has been a while since I last re-read this so correct me if I'm wrong." The ML said he decided he wanted to be with MC no matter what, even before he was diagnosed as an omega. So it's less "Beta's are bad" as a universal truth, and more "I'm a beta, and my crush is an alpha, therefore, being a beta is bad."
I read this manga multiple times but this time I thought that the message is kinda sexist.
When he was a beta a relationship wasn't possible but in the moment he's an omega everything rushed and than the drama appears and so on. But they lived each other since the beginning or? It feel strange for me because it's the opposite of normal bl where they have to go over the problems of not being in a heterosexual relationship, here the message is more "you can't have love when your the wrong gender"
Or do I understand that wrong?
Am yes the other message is "learn to communicate" ^^° they're very bad at this