First, let me explain a little bit about my situation. For atleast 2 hours every night, I have sex. Sometimes, I'll have sex 4-6 times within the day, other times I'll be up all night. I've noticed that in a day where I've had sex 2-3 times, it is a lot harder for me to keep an erection at night. Usually if I go soft, I simply transition into foreplay until I'm hard again. This generally happens without getting off and sometimes I'm simply not able to get hard again. So, my question would be: Is this normal and would I want to seek some sort of natural stimulant? I love pleasing my girlfriend and she definately demands a lot of me sexually.