You showed up, that is a good thing, I posted a few pics of myself a while back and not to brag but as a muscular guy I sweat very easily. I dont know why but if I eat a nice big steak my body starts to tear it up and sweat. But anyways in situations where its going to be hot, I always wear Black shirts, I hate sweat stains in my shirts. I usally carry a few small paper towels or something to wipe the sweat. Now if you have a beard, goatee or stubble be careful when you wipe the sweat off your face as little paper peices will get stuck there and you will look like an ass.
Next time, go hang out , say hello to your lady, atleast let her know you came and wanted to say hi, then hang out inside, or in the shade and if and when its times to go tell her goodbye nicely and leave.
She has to feel like you made that effort