Condom

I have a really important question. When my boyfriend and I have sex, he always wears a condom. And he's pretty big, you know. So he picks the right size and everything and when he goes it, it's okay, BUT when he goes out, a big part of the condom is ahead, you know? He's uncircumcised and he told me it was because of his foreskin and that's what his mom's husband said too. And it's not like the condom was slipping off Because it's still thought on the base of his penis!