Some friendships are not outrightly sinful, they just make you run slower; they are weights and weights reduce your pace. You want to move on to the next level but you want to promote a friendship that is weighing you down into that season with you. Soon you find that you keep having to play catch up with that friend. You are running, she is walking. You are weighed by guilt of maybe I am not a good friend, so you go back to pull her to join you on your pace but she cannot catch up, she cannot take a run. You find that you are hiccuping through life. Running fast one minute, strolling the next. You are trying to strike that balance between being a good friend and being loyal to your future. None should suffer.
Part of being an adult is taking tough choices and being faithful to your truth. The truth is that friendship cannot co-exist with the growth you need for this season of your life.
Keep running, and by default your life and your results will inspire her to come up to that pace where you both are running together .