This sounds like one of the instances of the devs trying to make the game feel more alive, but inadvertantly made the sims appear incredibly stupid for having no situational awareness. In real life when you ask the popular kid out, you know that your chances are slim. You wouldn't develop a festering grudge against them, but just move on. No idea how to remedy this, though. We're told that having too relationships can cause lag, so how much more lag would happen if in addition remembering their friends the sims would have to remember who is friends with their friends.