Shouldn't most friendships go both ways?

Let's rewind. Flashback to middle school. I'm starting to play a competitive sport and simultaneously have been kicked out of my friend group for reasons unknown. Competitive sports carried on throughout high school and having friends didn't exist. Friday nights were spent with my Dad at the town movie theater and then crying afterwards during pizza dinners due to having no friends and feeling bad for myself (looking back I am so thankful for this time with my Dad rather than hs parties in the woods). College happens, I'm on a sports team, and have an amazing roommate. We do everything together and she becomes my best friend at school. I also start to make other friends and realize people in my high school were just pieces of **** and it wasn't my fault I was alone. Graduation hits, and my roommate and I decide to live in different cities. I kept the texting up for the first year, was always the one to reach out first and was always inviting her to my city for visits and always organized the plans. It's been over two and 1/2 years since graduation and she has not once invited me to visit her city and she has visited me about 4 times now. She also never has made any effort to introduce me to any of her new friends and will leave me on read for weeks if not months. I know she still considers me a best friend but I can slowly feel us drifting apart. I have just given up reaching out at this point and know she will just pop back in every month or so, so I just wait. I know she is responding to other people in a timely manner but I just don't understand why I'm always on pause. Do some friendships just fizzle or is ok to fight for a friendship to stay strong?