Why does it hurt so bad?

Ok every time my boyfriend and I have sex it hurts. Not so much because he's stretching me but because he's too long or something  and he hits what feels like my insides like my intestines or something ha. But anyways, is there a way to stop this from happening? Will it ever go away? He's a new partner so maybe my body just has to get use to him? I just feel like I can't have a good time because it hurts so bad