Dealing with a clueless man ??

Hello, so I recently started sleeping with a new person in a friends with benefits situation I guess. He’s really nice and sweet but I do have an issue with his maturity level. I discovered that he doesn’t know a lot of things about women’s bodies for example, he didn’t know that when women become pregnant they no longer have a period for the duration of the pregnancy. Also when I told him I was on my period today and that’s why I didn’t want to have sex, he made a grossed out face as if it was unnatural or something and then was like, “oh I’m not supposed to say ew am I?” Little things he does like that are beginning to bug me. He is foreign from Vietnam so I don’t know if it is a cultural thing where women don’t talk about their bodies as much ? But it is kind of shocking to me as we are both 21 year old adults. I don’t expect him to know everything about women of course but it’s just strange to me. Not sure how to go about this.