I have always been a one chance person. I give people one chance to show me who they are and if what I see is a clear indication of a future of problems then I excuse myself from that relationship.
When someone shows you who they are, believe them.
People often say well everyone has bad days and that is true but your bad day has nothing to do with me and I shouldn't be on the receiving end of your emotional dysregulation and inability to function like a rational, healthy human being.
1/
Your bad day, your lack of coffee, your lack of sleep, your whatever excuse you have for mistreating someone or being unable to control yourself ... shouldn't be something that spills over into the lives of other people who have done nothing to deserve being caught up in a whirlwind of what is essentially your inability to function in a healthy way.
If you think your friends are there to be your punching bag when you're feeling "off" then I'd say you're not a very good friend.
2/
If you need caffeine to treat people properly then you have an ADDICTION problem and a substance abuse problem and that is not an excuse to be rude and unkind to people ... it means you need help and you need to look at your life and what kind of life needs some chemical substance in your body before you can act like a functional, rational, and healthy human being.
Your dysregulation should not become another person's problem. You shouldn't be taking out your unresolved issues on others.
3/
People who act inappropriately because of "a bad day" are people who don't care about how they treat other people. They aren't people who engage in self care so that they can be their best for the sake of others. Other people don't figure into how they live their lives or how they express themselves.
Such people are quite selfish and self centered and feel that it's other people's responsibility to deal with or accept them but not their responsibility to become a better human being.
4/
I am not interested in having selfish people in my life.
I am not interested in having people in my life that give no thought to how their actions affect other people.
I am not interested in having people in my life that won't do the work they need to do on themselves to be regulated, rational, and reasonable.
It's not about being perfect all the time. It's about being considerate of others all the time. It's about being aware that you're not the only person who matters in the world.