She didn't leave because she didn't love you. She left because she deserves much more than you're willing to provide. She deserves someone who loves and cares for her as she does them.
Someone who puts in effort and makes time for her, not someone who sees her when they want something or have nothing else to do. Someone who's consistent, not someone who treats her right some days, like crap others. Someone who appreciates her. Someone who actually cares whether or not she goes to bed sad. Someone who says "I love you" every night and actually proves it every day.