Trouble orgasming

Right, I hear so many people on this app saying that they cum so quickly before their partner. And I'm just sat here in amazement because I never am able to orgasm during sex. I can do it myself grinding on something, but not sex.
And it's not that my boyfriend doesn't try, he does EVERYTHING he theoretically should. Plays with my clit, hits it right, and does little things to turn my on like slapping my ass etc. And there's nothing more I want than to sleep with him so it's definitely not that I'm not attracted to him he is my world.
So my question is- if you can't orgasm during sex but can on your own, is it the guy not doing it right, that it simply doesn't work for you that way, or something else?

Vote below to see results!