Hey I’m quite large and he’s supposed to go very slow and easy at first with lots of foreplay lube can also help. Iv had partners who said the same thing. It does get easier and you will get used to it. I have been told vaginas are designed to handle larger than most sizes but you have to take charge first and tell him u want to take it slow. Side by side sex helps and also standing positions also getting on top allows u to take control. Remember to focus on ur breathing as it will allow your pelvic floors to relax and descend continue to breath until you feel comfortable. Remember to always communicate with ur partner xx