Helping my boyfriend

So my boyfriend is about average size and the sex with him is amazing !! But he always feels bad when I can’t finish and blames himself for finishing too fast. I need help trying to explain to him that a female body is way different from a guys and that we can’t cum just by penetration most of the time and that it also takes a while for things to build up before we reach climax. Can someone help me explain it to him , it was mean a lot if someone else can put it into words he might understand