Female led relationships discussion

Hi everyone! My BF and I have been doing male chastity for roughly six weeks. Since I’m naturally submissive and he’s a natural Dominant, flipping the power dynamic has felt really nice for both of us. Anyway, last night we did some T&D where he was tied to the bed, which went wonderfully! He got so hard that I thought his cage (a CB6ks) might break. Eventually, I took it off because I love having sex with him…I straddled him and rode until I finished, then kept going until he was nearly there too, before hopping off just in time to stop him from cumming. It worked twice! The third time wasn’t so lucky. He told me he was about to ejaculate, so I quickly hopped off and gripped his cock tightly at the base to prevent it, but it didn’t help. He shot right through my grip and then dribbled quite hard afterward. He definitely shouldn’t have cummed. Needless to say, I was pretty let down. Did I do something wrong? For punishment, I left him tied up and put an ice-cold washcloth over his cock…but the thing wouldn’t go down!!! After a while, I untied him (I guess keeping him bound kept him aroused, ha!) His cock finally went soft enough for me to make him lock himself back in as extra punishment, since he struggles with clicking the lock on his own—I think it’s natural not wanting to put your cock away again! Later, we were cuddling on the couch and I asked how the orgasm felt. He said it wasn’t quite as good as a full one, so I believe I achieved my first successful ruined orgasm, though I’m not 100% sure because his initial spurt was strong. Does anyone have any thoughts or suggestions on what I could do differently next time? Any advice would be greatly appreciated!