18 year old girl cries out - Boyfriend is pressurizing her to give him anal sex

My boyfriend of 5 months and I have a great relationship and a very open minded sex life. If one of us wants to try anything at all, we clearly communicate it, try it, and then reflect on whether we liked it or not. He was really curious about anal and I was 80% sure I wouldn't like it but I tried anyway because you never know until you try.