why do i go soft sometimes with my girlfriend?

[ninja12345]

I have a question.. i am 20 years old and i am with my first and only girlfriend for about 6 months now. she is about 17, well we are very much in love and very close, and she HAS had sex in the past and i havent. well we've discussed it that we are going to wait, because i dont feel ready... the reason why is whenever i kiss her i'll get hard, or whenever we get intimate, but for some reason this is what i dont get... i'll go soft, either all the way, or semi, whenever i try putting it in her, or even if she is just rubbing against my penis..i'll be fine if i get head, but i'll go soft whenever i go down on her.. why is it that i have this problem? is it a fear of sex, or something else?? i'd appreciate the help, thanks.

[Jasperky]

It's probably a matter of stimulation. You might be stimulated when kissing (some people get aroused by lip contact) but the time taken for her to descend, or whenever she rubs, there might be less stimulation. Maybe she rubs the wrong area, in which case, try and get her to touch somewhere else (usually the bottom of the head of the penis is sensitive).