Is something wrong with my vagina, sex hurts!?

the actual penetration hurts, not anything inside the cervix. he's rather large, uses magnum condoms, so that might be it, but seems like it shouldn't de so difficult. we use lube, and i'm always sufficiently aroused, and i'm really comfortable with him, and he is really gentle, so i'm not sure what the problem is. he's the only guy i've had sex with