COULDNT GET IT IN

Alysha
so last night and my boyfriend decided to have sex for the first time, he got the condom on and shit and we were ready to do it. but when he tried putting it in tr just wouldn't go in??? like it would just slip away, so like i trieed to guide it in but still nothing would happen? do note he was extremely hard and really big so maybe that was the problem. I DONT KNOW BUT WERE CONFUSED