I m 16 been with my boyf for a yr the last 6mths have been getting pain durin sex and dnt wanna do it anymore?

i found out i have extremely low iron, which might be a factor but i dont know why it hurts or why i dont wanna do it anymore, or why i dont feel i need to i think im just to comfortable with him, but he still wants to do it all the time and is starting to get sick or me just auto matically saying no before he asks simply because i dont wanna do it!