"The road goes both ways." I have heard this saying in relationships, friendships, etc. No one likes to put in all the effort. No one likes things to be one-sided. If they are, that is where issues start to arise.
I had many one-sided friendships. When we were friends, I didn't notice it as much, but then when it all ended it hit me like a truck. That might just how you deal with your friendships, but I am not like that. If I am the one constantly texting or calling first, or notice if I don't do these things and I don't hear from you, you know I am done.
What's the point of putting effort into something, especially when the other person could care less?
It's all about giving and receiving. You can't just keep taking, taking and taking. That is not what a friendship is about. Not to me, at least. Personally, friendships to me mean you both have trust in the other, go to each other for help, reach out to one another, love each other, and just always be there for the other person no matter what.
If everything is one-sided then it's not a friendship.
Maybe you are in a friendship with yourself, but definitely not the other person. Therefore, if that person doesn't even acknowledge your presence, don't waste your time.
In other words, if that person doesn't realize your absence from their life, then they won't be aware of your presence. Dedicate your time and effort to someone who will do the same for you.
Don't go chasing someone.