Damn it

My partner and I agreed somewhat to have an open relationship and started profiles on Tinder. We set rules and boundaries and everything was fine until I got a match. I felt sick, physically sick and realised after all the weird excitement of it all I couldn't do it. Even thinking of him sleeping with another person I couldn't stomach it. So, I told him and we both deleted the profiles. I'm extremely angry with myself, because I feel like I'm holding him back from having fun, from having a fling every now and then since our sex life appareantly "Is monotonous every now and then" and I think that's due to him being my first. I hate feeling like this, I feel like he would be better off without me.