I had a best friend, probably the closest I've ever had. We did absolutely everything together, from going on dates to even showering.
A lot of people were shocked when on New Years she started complaining to me about how I hadn't been spending enough time with her (I hadn't seen her in about a month because all of my other friends were complaining about neglect) and I completely threw her down the stairs of realization, being a little harsh while doing so..
To sum it up, I pretty much disowned her because of the way she was conducting herself as if I owed her my attention 24/7, she treated me as if I were her boyfriend, she expected me to spend my time and money on her and do just about everything with her.
It exhausted me, but here I about seven months later experiencing the same problems, just with new people.