Help!

So my bf and I have been dating for about 3 months and I’m not sure how to approach him about our sex life. He’s 28 and struggles staying hard and has never actually came during sex. I don’t know if it’s because when he was younger he did a lot of drugs and drank or if it’s something to do with me or? I don’t want to hurt his feelings because I’m sure it’s an insecurity. I do however want him to be able to finish and last longer.