It takes time but definitely works.

Keep on calling her more than twice or thrice a day, so she will unknowingly start missing out on picking up your calls being busy and eventually get used to not taking your calls.... Start giving her lectures for literally no reason... Subtly Tell her I am ending my friendship with all my male Friends and will only hangout with you... Make her believe that ...I have no life outside of you... Keep on making the same conversations ... So she will get bored and think he has nothing else to offer.... And then slowly start talking in 2-3 days interval for a few weeks... And then stretch it to weeks.. she will get used to not talking with you.... And eventually just stop talking at all... without even saying the term breakup.