Hate to break this to you, but sexual desire doesn't stay the same your whole life. I mean, for some few people it does, but for most of us we go through different periods of desire, and as we age we get busier and busier with other things and time become a factor and then we get even older and we've done it so often other things about our relationships take precedence. You're entering adulthood. You also can't judge your erection by masturbation, and the fact you're masturbating for reasons other than sexual arousal, which is fine, says a lot about your situation -- you're not really all that turned on, you're just habitually masturbating for relaxation or proof of concept so to speak. You need to chill about it, and know that the real test only comes when you're with a partner, not when you're by yourself. If you find someone you like and you can't perform then, you might have a problem. Breakups bring a lot of emotional angst and can also affect our self-esteem. They radically change our habits, as we go from having a reliably available partner to not having one. Just relax, live your life, and when you meet someone new you like things will probably be fine. And there is some hint in your post that you kind of look at sex as a contest. If you do that, it will become one, and contests have winners and losers and lots of pressure. Sex isn't a contest. Peace.
As long as ED is not real I am fine with anything guys. Hope everybody who passes by has something to say about it