Partner dancing with other women.

So my partner and I were at a friends wedding last week. And he had abit to drink. I wasn't drinking so I defiantly wasn't on the same level as him. Everyone's on the dance floor and I'm sitting with friends a little bit away and start seeing my partner dance with 3 older women our friends mums to be exact. I couldn't tell if he was fully up close or a little bit away but basically doing the grinding motion. I was shocked and hurt to watch this. And also let one of the ladies take his buttoned shirt off. He says he couldn't help that. I'm struggling to get over this so much. It's always on my mind. I don't know if my partner fully understands how much this hurt me. But it just makes me feel worried that if he was ok doing this while I was there. How do I know he doesn't do things when I'm not there. It's just really heavily weighing on my mind.