When I am in the gym, I dont know about the rest of the guys, I am pretty stand-offish with girls. I get myself in a pretty fired up mood to be able to push some weight around, that I am not the most personable person to talk to.

Just go up and ask him if he will spot you on something, that should help. More skin also helps, but I dont advocate that with girls in the gym, because it distracts me from my work.... :naughty:

:edit:
Unless you consider one riding you while on a weight bench working out... that is completely acceptable.