I think this goes to show one of the perils of polyamory. I’ve been part of it myself, and I think that it can be done well, that it can be validating and affirming and not cause people to feel lesser.
However.
I think it’s more common in polyamory that one or more partners feel like “an option, not the option”.
Because in polyamory ALL partners are merely “an” option. And there is no “the” option. Unless you do polyfidelity.
It seems like maybe you actually want a monogamous relationship, or wanted to be this man’s “primary” when he actually wanted a casual relationship, or at least didn’t want to make you the #1 in his life.
Mismatch of what you both wanted maybe. Not necessarily saying you’re bad. It’s just how polyamory (unless it’s polyfidelity) goes sometimes.
It’s one reason I’m not poly anymore.