My boyfriend said I felt "loose" last night, what could be the cause?

Yesterday my boyfriend and I had sex. He was arousing me for a while with his fingers which was really turning me on. We started having sex and afterwards he started acting weird/distant. I asked him what was wrong and he said that my vagina "felt loose like I just got fucked". It made me feel extremely insecure as he said "it doesn't usually feel like that". He began making assumptions that I did something with someone else because the way I "felt". I was extremely confused as I hadn't done anything differently other than not drinking as much water. He's upset at me and accusing me of cheating. I tried to explain to him that I have no control of how I feel down there and I'm just extremely insecure now. What could be the cause of that or how do even go about this? 😔