When you are a rejected it is quite possible that you can go though the symptoms that you are experiencing. Do not let them get you down but rather look forward to finding another partner that you can have a deep and intimate relationship with.
For some men the sexual experience is part of deep intimacy, as opposed to others who are like dogs looking for a bitch on heat, and when the intimacy is not there, there is no real interest and so arousal does not occur properly.