1. People who can never remember when your birthday is.
If someone you regularly hang out with can't be bothered to remember your birthday, or what it is you do at work these days, or what the name of your coffee shop crush is, or how much money s/he owes you, consider that this person might not be so much your friend as s/he is a mere body to which you are sometimes adjacent. Friends (at least sometimes!) do things for you that inconvenience them. Friends take up valuable memory hard drive space for you. Of COURSE levels vary, and we won't have the same expectations of the high school friends we see twice annually, but if you're hanging out with someone regularly and they don't seem to know ANYthing that's going on with you, why?
2. People who can't stop correcting you.
You know when someone's like, "ACTUALLY, it's pronounced hoo-moose, not hum-us"? First of all, nobody normal says it like that, so shut up. Second of all, what we mean here is that it's exhausting (and dispiriting!) to be friends with someone who consistently makes you feel stupid. These are the know-it-alls, and the people who make you feel like you should be ashamed for not having read whatever book or seen whatever documentary. These are the people who REFUSE to acknowledge that you're capable of understanding whatever it is they're trying to say. Conversations with these people are heavy on interruption and the dismissive "wellllllll" and light on anything enjoyable.
3. People who wait for YOU to make plans (and then almost always cancel).
Check out your text history. Is it noticeably one-sided? Filled with various iterations of the "I'm so sorry, I'm the WORST, but I actually need to bail tonight" message? The thing is, habitually blowing someone off IS the worst, and acknowledging it isn't enough to fix it. Everyone in the whole world is busy, which is why we carve out time specifically for the people we love. It's important, and it's necessary. Prioritize the people who prioritize you.
4. People who never want to do what you want to do.
Listen, there's no inherently bad pastime (unless, I don't know, you're really into bullying? Or murder?). But if your friend wants to dance until 3 in the morning, and you're really in the mood for some Cards Against Humanity, or if, when Friday comes around, she's begging you to join her in a loud bar with some stiff drinks and you'd rather stay home with your new vaporizer and your backed-up Hulu queue, there's a bigger issue at hand. Free time is a limited and valuable commodity, and if the ways in which you and your friend choose to spend it are incompatible, it might speak to your own incompatibility. People change, as do their habits, and if neither of you are into compromising, it's time to move on.
5. People who never tell you why they're mad, even though you know they're so mad.
Is this a conversation you want to have upward of 2,000 times in the span of a few years?
You: "What's wrong?"
You: "It seems like you're mad at me?"
Friend: "Well I'M NOT."
Confrontations are not easy, but the ability to have them is pretty much mandatory for any close relationship. It is better to have them (and make friends with people who can have them) than to simmer with rage, in silence, until all our hair falls out and our bones shrivel and we die.
6. People who will only hang out with you when their S.O. is completely unavailable and/or out of the country.
You are going to see your friends less often when they're in romantic relationships, probably, and it is going to be so stupid. But a little understandable. But a lot stupid. But if you're seeing them WAY less often, and are being canceled on in circumstances like the time Carrie bailed on dinner with Miranda so she could cook veal with Big (leaving aside the fact that this worked out well for Miranda because that's when Miranda met Steve, but that's beside the point), that's bullshit. Maintaining strong friendships while in a romantic relationship can be challenging, so it's great to find people who will actually work at it rather than squeezing you in only when there is literally no way to hang out with their significant other that night.
7. People who can't be happy for you.
The world offers MORE THAN ENOUGH sources of judgment (hello and welcome to the internet) and the people you keep close to you should be your respite. Your friends are meant to be your champions, genuinely and reliably, so if the congratulatory messages you're receiving are laced with resentment ("You're so lucky to work in an industry that promotes people so quickly!") or negated by subtle insults ("Oh, is that a good grad program? Huh.") it's time to question just how invested that person is in your happiness. And they should be super invested! Because the cool things about friends is that their happiness is also yours, and vice versa.
8. People who never ask how YOUR day/weekend/life was.
Most of us are guilty of talking about ourselves too much. The price we pay for doing this, at the very end of describing in great detail our fascinating dreams or whatever, is to ask our friends how THEY'RE doing, what's new with THEM, and to really care about the answers. Some people forget ("forget") about this part of the exchange, and will simply continue talking about themselves for as long as your face stays within 10 feet of theirs. Sometimes it takes a while to notice what is going on, because these people are often very good at making it SEEM like you're talking about things besides them. This is a great and also very evil skill.
9. People who make you feel like everything is the worst.
There's nothing wrong with a healthy dose of skepticism, and of course we aren't suggesting you surround yourself with unrelenting optimists. If nothing else, things would get very boring very quickly. But you know what else is boring? Making a habit of assuming the worst in both people and circumstances. So when your buddy's default is extreme negativity, you're put in the position of either joining him there or being the upper to his Debbie Downer — and both are pretty exhausting.
10. People whom you can't trust as far as you can throw them.
Is this the correct saying? Who can really throw anyone, is a fair question. But sometimes you meet someone, and become friends sort of, and you notice that s/he seems really nice to YOU, but talks complete shit about everyone else all the time, and is generally pretty mean, and then you see him or her be nice to the people s/he was talking shit to you abou earlier, and you realize: This person is almost CERTAINLY talking massive shit about you too. Just not to your face. A true friend talks shit to your face.