boyfriend wants unprotected sex & I don’t

So my boyfriend wants to have unprotected sex & I don’t feel comfortable doing it at least just yet. I’m on birth control & I take it everyday so there’s a slim chance to getting pregnant but I would just rather not take the chance of me being the 1% , and I don’t even like taking chances. I think he’s starting to get frustrated because I always say no. I just don’t understand what’s the big deal about using a condom? What am I supposed to tell him next time he asks