I need help ..

So everytime I have sex with my boyfriend and he tries to go all the way in I always get a really bad pain when he penetrates , I’m really tired of it hurting like I just want to have a good time but I cant due to that pain , what should I do is there anything that I can do or what can that possibly be ? And I never tend to have pleasure over having a sex either so i really don’t know I need some advice.