We should love everyone because we're meant to follow Jesus' example and He loves everyone unconditionally. No matter how annoying or awful they are to you, you should still do the best you can to love them. Find parts of them that you can love or love them because you know God loves them. This does not mean at all that if you are dealing with issues like abuse that you should stay with the abusive person because God commanded you to love them. Take care of yourself, don't just let the other person hurt you, but try to forgive and love them even thought they have don't awful things to you. Loving someone doesn't mean you have to be best friends with someone. When you love someone you see them as a person with flaws but with good parts as well, it means you respect and care about them no matter what they do. I don't mean respect them as look up to them but treat them politely and like a person who means something. Love others like God loves all of us. There isn't one person who God looks over or doesn't love.