Quoting grizzy:" Maybe it's the hitting of your cervix which can cause pain and pleasure since it's more sensitive at ... [snip!] ... up.. for me it's painful at first because my insides are being stretched but later the pleasure kicks in and use tons of lube."
trust me, we do start off slow lol. It doesnt like to fit at the beginning so i have to do it little by little and just let it sit in there to get used to it. hahah. But, i'm sure thats what he's hitting. We had this problem, before i got pregnant. But, before it just totally hurt, non pleasure.