Human stupidity can be astounding, mind boggling and downright ridiculous. There are so many things in life that are brought about by our own actions, choices and words - so many things that could be avoided altogether in favour of a workable solution.
There are only a few things that commonly trigger conflicts and disputes and in these few things we can include money (incl wealth, property, income etc), sex, honesty/dishonesty and emotions. Very often 2 or more of these things are all wound up together and you end up facing a huge mess of mitigating factors. How often do friendships end because of one or more of these things? How often do relationships end because of one or more of these things? How often do people sabotage their own lives with one or more of these things? Pretty damn often.
Our tendency is really a strange one: we tend to take all sorts of things incredible personally, completely irrationally, to the degree that we will end a relationship with someone we've known for years. When it comes to money, you often find that the emotions thing is involved too because it's usually about jealousy/envy or greed that we sabotage our lives. If you're rich, you feel threatened when another person (even if its a good friend) says or does a certain thing. Your wealth becomes its own person, taking on a life and personality within your mind and you tend to want to overly protect it and keep it safe (the only way you can keep it safe, in your mind, is if it's YOURS). On the other side of the coin, you may not be so fortunate and then envy your richer friends, which will inevitably seep into your communication and interactions with them.
Sex has become another big entity hovering over us. Sex is no longer about procreation or enjoyment, now people have all these ideas of what it should be that they take from movies, books, porn, etc (Just think of that movie Don Jon - men tend to fantasize that sex should be how it is in porn and women tend to fantasize that sex should be like it is portrayed in romantic movies).
Sometimes people are dishonest. Sometimes you lie to your family, your partner, your friends, your kids, coworkers, but most often you lie to yourself. Sometimes you do it to protect yourself or your loved one, but sometimes you do it to hide the truth of what you really did / who you really are - now these are the ones that usually cause trouble for all involved. When you start deceiving people for "selfish" reasons, they are probably never going to trust you again (when they find out). This is usually enough to end a relationship and create mounds of conflict.
The last one, emotions, is possibly the silliest of all the reasons listed above. This is where you take things personally, make assumptions, or jump to conclusions about what other people say, do, how they act, etc. This is the one where the little voice in your head starts whispering "what if's" in your ear and you start this whole internal dialogue (with yourself) about what you think the other person meant when they did whatever they did. It's like seeing your current partner talking to one of their ex'es, but you can't hear what they're saying. You start creating this story in your mind of what they might be talking about, and it usually involves something that you fear (like them talking about how much they still feel for each other) is happening. In reality, things are seldom what you think they are, but the problem is that you so often make assumptions first and get the facts later, usually creating a whole lot of conflict in the middle.
These things are so unnecessary. Imagine how much sorrow could be avoided if we were to behave like rational beings and not have our default setting set to "idjit". How much of the large scale conflict in this world is due to a few stupid actions of a handful of people, who are more intent on keeping face than they are one creating peace? This is not a rare thing - it is a global epidemic that can only be solved by all of us deliberately changing ourselves to stop doing the silly things we do that lead to big heartache.