Hello Jaideep Thank you for getting in touch with us. As I see, you have been having erectile dysfunction. As your young age, these problems are usually psychological and out of fear. If it happens once with an individual, a fear sets in and then that person is not able to experience a proper erection again. As you have mentioned, you have no problems with erection during masturbation and this problem arises only during sex. Therefore, we would recommend you to relax and get the fear out of your mind. If it still persists, you can get in touch with your Doctor who might conduct some tests if the need arises. But just remember that we think its the fear which is holding you back. Hope this helped. Regards Dr. Gagandeep Dhillon