My partner and I opened up our relationship a few months ago. she dated my best friend until they disastrously broke up a month back. i was a little bothered by it at first but quickly got over it cause i love them both (though him only platonically)

she's been getting really into relationship anarchy lately and dating a few other guys. (on the other hand, i have been on two dates where i got catfished, then got ghosted by someone i really started falling for, and have struggled with finding anyone else even remotely interested in me. which all in all makes me feel really unattractive and undesirable but i digress)

one of the guys she's been seeing seems nice enough but i'm honestly jealous that she seems so into him

the other day, she told me she doesn't see our relationship as "first and foremost" but as a non-hierarchical dynamic because she has additional people in her love life

this really hurt me because i've always viewed ourselves as our "first and foremost" rather than "one and only". we live together, we've been together for several years, we have gone through milestone moments in our lives together. i have plans to propose in the next few months

i never wanna lose her so i wanna try understanding and unlearning relationship hierarchy and embracing relationship anarchy

but i don't know how

i could use some help. does anyone have any resources for learning to let go of hierarchy?