When interacting with people, it is always good practice to ask yourself: "Does this person measure up to my standards?" Then hold them to those standards - don't simply shrug and stay around them because of some form of social inertia. Decide whether you want to continue staying around them or not.
If not: have the guts to walk away.
Not too long ago a woman I was fucking mentioned that she was surprised that I chose her (ie that I was out of her league). I told her that I have quite high standards (ie she met my criteria and that I don't just fuck anything). Thankfully, it went to her head.
Soon afterwards she violated my standards: she had a shit-fit over a text that I sent in response to a slightly risqué picture she sent me of her in her panties (I was distracted instead of kissing her pussy/ass). At that point I realised that she no longer met my standards (of maturity and common sense) and walked away from her without a qualm.
The drama-queen horseshit that ensued over the next two days really cemented that as the best decision I could have made. I dodged a bullet from a grade-A nutjob, one who hid it very well. Goodbye Princess NutJob, have fun storming the castle...err...getting fucked by someone else.
There's probably only one solid question about a person: do they add value to your life. "No" means that you shouldn't waste much if any time with them. "Yes" means that you should make an attempt to spend at least some time with them - assuming they are interested. (Some people are simply too busy: let them go, with some regret, but don't lose touch with them if you can help it. It might develop later on.)
Standards are on a sliding scale depending on the relationship (roughly as follows):
• long-term girlfriend
• close friend (don't let others break up your friendships)
• short-term girlfriend
• someone you've only just or never met (common courtesy and decency)
There are standards which shouldn't be broken in any company (like being a real dick/cunt - when they're violated the only possible response is to say "classy" or "charming" in a dry tone and walk away, shaking your head). The closer someone is to you, the higher the standards and the stricter your enforcement of those standards.
In more intimate relationships, the highest standards of all should apply. Bluntly, this person is supposed to be your (hopefully mutual) partner. Someone to share with and build something with that protects you both against the random shit happenings of the world. (I sound like such a fucking romantic.)
Yet, too many people let their intimate people treat them like shit. Family treat them like shit. Friends treat them like shit. Boy- or girl-friends treat them like shit. And they take it, for whatever reasons there might be (in their creepy little fucked-up minds).
By allowing that treatment they are exposing their inner shitty values: "I don't deserve better because I am shit."
Seriously? Are you really shit? Right, I will take you at your self-evaluation.
Up your standards. Enforce them. Even if it causes temporary pain (like losing friends) the result will be long-term pleasure (gaining better friends). In the long run, you will benefit from it.