i did something i knew my partner wouldn't like

so my partner and i have been together for a couple years now. things are generally good between us. we're both into trying new stuff but not super experimental or anything, you know? so i was at this party with some friends from college. nothing major just hanging out drinking talking about old times and stuff. one of the people there mentioned they had this friend who did rope bondage as a kink and it got me thinking. i've always kinda wanted to try that but never had anyone interested or whatever. so i reached out to this person after the party, just asking if maybe we could set something up for next weekend. long story short we did, with my partner's consent of course. but when they found out what it was exactly, they were not happy at all. they felt like i betrayed them by doing this behind their back and not really telling them first. but honestly i thought if i told them upfront, they'd be against it completely so i kind of hid it from them til we could figure out details and get set up with consent and all that. i know my partner is feeling hurt and confused right now. but i feel like i had to do this for myself to explore something new. maybe next time i'll be more upfront, but honestly at the time it felt necessary to me.