How we get erection?

I just read an article about premature ejection, the article says cause the main reason male get an erection is the urge of the climax level of dopamine, so what do men do when they are having sex? Yeah, your body just craves for the climax instead of trying to last longer even you are thinking about baseball game when you are at the edge.
I normally get an erection by sexual fantasy, so I give it a test that if I can get a boner just for fulfilling the pleasure and need of my partner, for love. And I can just do it like half as hard as I usually can, and it didn't last long which makes me curious about the question, do we keep using the wrong way to get an erection? I mean it like we are familiar with getting an erection for ourself, but for the one we love? Not so much.
Peace