If we lived in a perfect world, it would make no difference what other people think about one another. I would love to go through life not caring what other people think about me. Unfortunately, this isn't always the way things work out. Humans are social beings and as such, we are programmed to listen to others.
In the world of dating, there is always one friend with a significant other you aren't a big fan of. While you can control who you like, it is hard to control what your friends think of someone. When first meeting a friend's boyfriend, you want them to have an interest in becoming friends with you, and you want to see that they genuinely care about your friend.