solo-poly, but not by choice

my (20) partner (19) are polyamorous and while i came into the relationship monogamous, i realized i liked being poly too. i still do have jealousy and communication issues i need to work through, but otherwise i don’t really care what my partner does

he’s had multiple partners since we’ve been dating, and i haven’t had any. i don’t mind that he’s with other people but it just makes me feel really sad and hopeless. he’s my first relationship fr, and that’s bc im just not desirable (imo) and sort of shy. they’re very handsome and outgoing and doesn’t have any problem making connections with people. they can walk up to a stranger and be friends by the end of it, and i really admire that trait about him

i’m just really sad that i haven’t had the same experience as him. i want to have other relationships and he actively encourages me to, but nobody has been romantically or sexually interested in me until i met him. so it’s safe to say that nothing has changed since then. it also amplifies my jealousy a bit when he is with his other partners, because i just wish i could find someone outside of him. idk how to go about this, i really do try a lot. i even tried to pursue things with some of his metamours (he doesn’t have a problem with this) and nothing became of that either. i’ve even considered breaking up with him because this hurts a lot. i don’t know what to do. i try not to throw pity parties for myself but i just want to be desirable. advice is appreciated but i needed to put this somewhere