A lot of guys get soft when they wear a condom. That's called condom-phobia. Quite a lot of men, it seems, have no trouble getting and maintaining an erection, until it's time for them to put that condom on. People sometimes find that the process of putting on a condom interrupts the flow of their love-making and their erection subsides. Some men cope with this by becoming comfortable with condoms and good at putting them on quickly. Some men do practice with condoms on their own when they are masturbating. Some other men find it easier to keep their erection if their partner helps them put the condom on. One key factor is to avoid thinking that penetration always happens as soon as the condom is on. Carrying on with foreplay after they have put the condom on and that gives time for the erection to come back. If you still have a problem when you don't have a condom, you may seek the advise of a doctor. They can prescribe medication to help you perform better. They can also help you diagnose whether this is happening because of stress, too much pressure to have sex or something else. Good luck!