Orgasm problem

I've been masturbating for years and never finished. I can do it for like 30 mins and I just can't reach the O. I've started being sexually active a month ago, with my friend with benefits. I swear to God his mouth is gold and so are his fingers but I always have to stop him because I can't handle the pleasure, it just feels like too much. Sometimes I try to let him doing his job but nothing happens in the end. I've heard that some women can't reach an orgasm, can this be a possibility to me?