I feel your pain, I`ve had both in person and online friendships that have gone similar routes as yours. But that is the nature of life. People change, circumstances change and improve. You really care about her and she cares about you and your other friend. I say keep in contact! Just because her mode of communicating has changed doesn`t mean you have to change. Sometimes we must keep friendships going if the other person doesn`t. I personally had dropped off in contacting people I cared for very much because of various issues and challenges I had in my own life. It didn`t mean I cared for them any less. But to them it may have looked like that but they never said anything. The bottom line is showing you care for a friend is never time wasted. Just be there for her and you keep the contact. Don`t say anything though. Friendship dynamics change overtime it`s ok it doesn`t mean anything is wrong. Good luck