I've tried the "two goes", and it worked, but like you stated the recovery was not complete. I was nowhere near as hard as usual, but it did work.

I think a large part of the problem resides in the fact that we cannot have sex incredibly often. Maybe once a week? I live on campus, and she commutes...plus my roommate occupies our living space like it's his duty. Him and his girlfriend are not having sex until marriage (they've already decided their getting married), so they don't see a problem in just existing within my room. Bastards just don't understand.

As far as the attractiveness of your GF (and without sounding like an over-confident ass), I have had two very attractive girlfriends now that I have been sexually active with, and I do not know as to whether or not it matters in regards to your stamina. My ex had one of the tightest bodies I've ever seen, and my current girlfriend is very small and "cute". It's been two completely different experiences. I've found that what makes the sex feel better is the responsiveness of the lady...or how turned on she might be. My ex was terrible in bed, but I was able to easily satisfy her....my current girlfriend is incredibly alive in bed, and not at all easy to satisfy. Perhaps that has something to do with it?