Difficult if not impossible to ejaculate during sex

I'm the same. In fact the only times I've ejaculated without self masturbating was the time I lost my virginity, and one time when I was in a Mutual Masturbation session.

Normally, when I'm having sex I can sense that I 'want' to climax, but I can also sense that it's not going to happen on its own, so I have to withdraw, masturbate myself up to the point where I can sense that it's about to some soon & that there's not going to be any stopping it. I then return to penetration & finish the job off that way.

Some people might think that it's beneficial for the partner to have someone who has enough stamina to keep going like that, but even so there are times when it starts to get the partners tired & sore if it goes on too long.

Regrettably it's nearly always the same when it's somebody else masturbating me. This is why I was so pleasantly surprised when one guy successfully brought me to orgasm by hand - something noone, male or female (I'm Bi) had ever managed to do with me ever before (or since).

Don't get me wrong, I really enjoy the sensation of all kinds of sexual activity & I can't get enough of it, so there's nothing wrong with the sex drive, it's just finishing off that's the problem.