Sex while I'm on my period

So this guy I know want to have sex today but I'm on my period. I was talking to my friend and she says that everything should be okay (he's using a condom and no I'm not on birth control yet. And I'm 14) I asked him about it and he said it's okay and that he doesn't mind but I don't know what to do. A big part of me wants to do it but them there is the other party that's like why don't you please