Why can’t I handle orgasms?

Whether I’m receiving oral sex or using a vibrator, when I climax, I can’t handle the sensation and immediately push away from it. Is this is normal?

I also noticed that I don’t cum. There is only one guy who could ever really make me cum, and he would have me wetting the bed. Now, while I still love sex very much with my new partner, I have never really cum with him. Just want to know if anyone else has experienced this and what to do about it.