Ever since I can remember, I used faulty judgment, unsound reasoning, and optimism to convince myself that it was okay to continue my friendship with very toxic people. I look for the best, I get too involved too quickly, and I can't imagine ever treating a person the way they have treated me--and so I made excuses, talked myself around the topic, and avoided what inevitably needed to be done: the cut off.
There were always signs for these people. Little things they did that should have set off warning bells in my head or opened my eyes or something... And so, after years of learning what these signs mean (and still every so often falling into the same trap), I hope that I can help someone get closer to realizing the true nature of someone or help them learn to reserving judgment. Of course, I don't want to be a cynic. I want to believe everyone is wonderful and I want to believe no one wants to hurt others, but these things are simply untrue. I'm not saying you should assume everyone is heartless, I'm saying you should wait to let them prove they aren't.
Do you feel as though they are your only real friend? This has been common in every toxic friendship I've ever been a part of. Other than my best friend, they would become my next closest friend and that would be it--I would feel myself drifting away from others or be so caught up in their drama I wouldn't see I was drifting away. I would talk to them a lot and spend most of my time with them. I would be so thankful for the friendship that I wouldn't see how this was bad. It's not wrong to have a couple close friends, but when you start to feel like you don't know how to make any more friends, that's when you have a problem.
Do they make you feel bad about yourself without realizing it? They might make a smart-ass comment or joke, but in the end it's always based in some truly hurtful insecurity of yours. I would never see it coming from them directly, but I would feel myself zoning into one of the things I didn't like about myself. They might've mentioned something about how I look or laugh or walk or talk, and suddenly I'd be thinking about it. This would only cause a domino effect where I would then be thinking about all the things I didn't like about myself, and next to them I would feel small. Friends bicker and tease, but the moment you feel yourself hating yourself, they're no longer being a friend.
Do you disagree with their morals or decisions, but don't know how to tell them? You've become invested in the friendship, but notice they start doing some things you disagree with and you're afraid to say anything. I can remember countless times I should've stood up and said something, but because of the nature of the friendship, I felt like I couldn't. While they could point out all my flaws, I couldn't do the same to them for a multitude of reasons: I was young, nervous, scared, afraid to lose them, not confident, unsure of myself, etc. There were so many little things that built up and ruined my confidence, I couldn't bring myself to stand up in what I believed in. If you see this happening to a friend or yourself, say something. Remember to always say something.
And lastly, do you ever ask yourself whether or not this is a good friendship? You find yourself questioning the friendship or doubting the person you're friends with. I know I went back and forth between yes and no for many of my friends. I was always unsure of whether I was overreacting or making the right decision. It was always hard for me to let go of someone, especially when I had come to care so much for them despite the fact they didn't feel the same about me. If you ever find yourself doubting a friendship, that would be the best indication you should leave it. Friendships shouldn't be hard enough to make you question them.
When I come to the conclusion that someone I'm friends with is toxic to me and my life, I cut them off. It may seem rude or unnecessary, but sometimes saying nothing and leaving is enough to make them realize what they did--and usually they already know how they have been abusing you, so they don't care when you do leave. They usually find someone else or continue on living their lives, but they won't care if you leave. I think that's the biggest thing anyone in that position needs to know. You think they'll care, that's why you don't leave, but they won't and you'll be free.