Yes, it's very common problem in young people. Due to various reasons they r not confident about getting Married. To decide about fitness, u need proper interrogation and physical examination. Then u should undergo various pathological test, like hormonal,
thyroid functions,
liver functions, blood glucose etc. Then u have to go for various test for normal Erection like PIPE test, office sld or rigiscan test. With all these test report, one can get correct information, about ur fitness for marriage.