Talking dirty

Samantha • Always avaliable for advice! Judgment free!<3
I have been with my boyfriend for 4 years now. I love him very much and I love having sex with him. Although sometimes I wish he would talk dirty to me but when I mention it he just says it embarrasses him. Which confuses me because it's been four years of us being together, and we were best friends for 2 years before we started dating. I'm just confused I guess, any advice??