This is from Amazing Spider-Man #583. You can view more scans from the issue here, but I've posted the one that gets to the sticking point to the left.
Betty and her friend Haley are clearly plastered. Peter takes Bettey out to get sobered up, but Haley? She's left with a dude she doesn't even know, and again, she's wasted. Sure, Haley may not have liked Peter, (she was supposed to be his date) he still shouldn't have left her wish some random dude who has a look on his face in the last panel that says "I'm gonna get me some tonight!"
Someone over at the Crawl Space hit the nail on the head, summing up Pete's actions as "Not my friend, not my problem."
Sure Peter makes mistakes, but he should be smarter than this. Heck, anyone knows what will more than likely happen in this scenario and even if we find out it doesn't happen in later issues, it still comes off as very bad judgment on Peter's part. I mean, if he's getting a hammered Betty out of there, why not Haley? Does not compute. It doesn't matter if Haley waved to be left alone with some dude, wasted girls tend to have bad things happen to them when meeting random dudes.