Break ups are not part of magick...Love spells cannot force another to do anything. As for breaking up with someone else? Just tell them, "I am no longer interested in you."
Get some courage.
Now if it is to break someone else up? Listen, people have their own life and can make their own decisions. If you are spending your time jealous of what someone else has, you are so fixated on that, you are not living your life and won't even take the chance to try to get a relationship yourself the natural way. Heck, you probably missed the opportunity of a life time.
Focus on your life, and do not waste your time focused on someone elses life.