Hi I Am A Virgin And I Have Been Trying

Hi I am a virgin and I have been trying to have sex with my boyfriend but every time he puts his penis inside me, my vagina opening hurts so much and also, he has only been able to put it in half way because it feels like something is stopping his penis inside me and my friends don't have this problem with their boyfriends and I'm really worried and it's causing me some stress so I'd just like to know what's going on and how to fix it