Whenever my girlfriend and I have sex, I can easily achieve a good erection but when it comes to putting a rubber on, my erection goes after a minute or two.                                                                                              It isn't due to the lack of feeling, or arousal but I always worry when i'm putting it on that I might lose it and/or it wont be as nice for her as it is when we don't use one (other contraceptives of course, but cannot use them anymore due to her medical reasons).                                                                                                              What might be the cause of my soft erections?                                                                                                                 Is there any way to prevent this or find a quick solution?