Original post by FeastfulIts not time that makes someone a best friend, its chemistry (which between you two, is very lacking). And this long length of time you've known each other, has created the illusion that there is much more of substance to the friendship than what ever actually existed.
1. (As a general side note)
A lot of friendships are born only through mutually shared circumstances/pursuits however what many people take a while to realize, is that the mutually shared circumstances/pursuits are the only depth the friendship has (and that depth is mostly an illusion; change the common circumstances/pursuit, and the friendship quickly crumbles/dissipates/grows distant).
Common shared stuff often boils down to "We work in the same department!", "We both go to the same school!" "We both love drinking and partying at the weekends!", "We live in the same close vicinity (same village, same dorm, same apartment etc)!", "We're both mutually lonely people (and hanging out with each other fills the void)" etc.
And what you will witness a lot as you grow older, is a great deal of friendships fizzling out as people's circumstances change. A really common deal changer is people having children; no longer having the will/time/money to go out partying at the weekends on the regular basis, the one main strong thing the group had in common (getting wasted) suddenly disappears (and so all the contact that was founded on it also begins to dry up). But then equally, now having children in common with other people, it creates new a circumstance for the parent to build new "friendships" on (and so suddenly you see a lot of parents social lives revolving around the shared fact with other people that they have children).
In the case of you and your friend, the only thing the friendship really has going for it is the length of time that you had known each other for (but what did you actually have in common? Very little- you're two very different people who have simply hung around this long because of shared circumstances). And now you're no long enjoying the company, it's quickly revealing how little of substance you two actually shared together.
What does this all mean? Were you actually friends before (and are you friends now)? How do you deal with all this?
I think there are different grades of "friendship" and that rather than having any real chemistry, most "friendships" actually just boil down to people sharing simple personal self-orientated needs/circumstances together combined with a general capability to get along together.
Getting along with people is quite easy, but it doesn't necessarily make for true friendship. And people and their circumstances change all the time (so that life will be full of stories of becoming closer to and then more distant from countless people over the years).
It sucks, but it's just a fact of life. But unless you've actually grown to really proactively dislike the person in question (in which case you will definitely be better off without them at all in your life), then deliberately burning any bridges (so for example making your annoyed feelings at your friend very known to them), will not reap you any dividends. Often the best thing is to simply to accept the change, stop putting so much effort into the friendship (the messages, the invites etc) and gracefully get on with your life in a cool, dignified & proactive way.
2. And this then leads to the next point: Considering that most friendships will become distant over time (not really enemies, but things eventually boiling down to a point of barely any contact or mutually requited interests etc), unless you want to end up feeling socially isolated, then you have to always be open to meeting and making new friends as you continue to advance through life. Be adaptable!
The challenge with this though, is that friendships which were once very close (or which lasted for a very long time) can be difficult to accept the decline & loss of and get over (in life, you can even sometimes suffer a sort of "mourning" period over the loss of friendships). And when an important (or at least once important!) friendship is reaching the end of it's natural life expectancy, your mental energies and efforts can become very focused on the declining friendship, so that instead of moving on and concentrating on much more productive/graspable life ends (making new friends, focusing on your work/education), you end up in a sort of life limbo as you pour a lot of effort/mental energy into a dead end friendship.
This is the worst sort of situation (when the difficulties experienced over a friendship meeting it's natural end, ends up harming/negatively impacting on your life).
You may feel some feelings of resentment towards this girl (disliking how little interest she has shown in you despite you spending a lot of time on her, etc) however the mistake is actually yours (for not standing up for more requited treatment in the friendship and not acknowledging/realizing the warning signs earlier). At this point, getting or feeling angry towards her will achieve nothing productive/positive for you. So now this friendship is ending, it's best to accept the status quo as much and best you can.