what the fuck do i do

ive only been in one relationship, that being my current girlfriend. we’ve been together for a year and a half and id do anything for her. but recently i met this guy and im in love with him too and i know he loves me back, but my gf isnt up for polyamory but i couldnt ever bring myself to leave her; but at the same time i want more experience out there in the dating world and i wanna just know whats it like to be with other people and have more experiences and learn more about myself. but she saved me and i couldnt leave her even if i wanted to