1. They've had enough
They have been stigmatised everywhere, they have had their hearts broken too many times, they have been told they're not good enough, they have experienced too much unhappiness and disappointment. They feel that nothing is right and want to escape from it. They turn to change, sometimes for the better sometimes for the worse.
2. Conforming to 'survival of the fittest'
These are the ones who got bullied in school, on the streets and even at work. Though some people may be able to appreciate them, but they feel that they need to step it up and be accepted by everyone else. They want to survive in this world, and so they turn to change. Flashback to when I was in primary school, where my friends turned to the "cooler" cliques in school and left me. Cruel, but they felt the need to conform.
3. They've found themselves
These are the ones who are lucky enough to have found themselves. It could be something they just got to know of or something gradually surfacing inside of them. They are comfortable in this newly found persona and don't care about what people think of them anymore. They're the ones who are finally happy and free.
You witnessed the drastic change of personality, perhaps from a formerly happy and bubbly personality to a sad and always preoccupied personality. Have they met someone new who could have inflicted such changes upon them? Were they just trying to help but unnoticingly caught this from this new friend? Conversely, they could have changed from a negative to a positive persona, again, depending on this 'new friend'.
These are the ones who were told they're ugly, be it just once or too many times. They're also the ones who think they're not good enough in their looks. Perhaps they think their features aren't refined or ideal enough like the models on the magazines, or it could also be how they dress. Flashback 4 years ago when I was told I was not fashionable enough. It triggered something in me having heard that, and I wanted to change how I clothed myself.
This depends on the circumstances of that person. When their lifestyle gets progressively busier, they tend to cultivate this cranky, easily irritable attitude. They are the people who complain about everything about the food they had in the 5-star restaurant. Alternatively, they could be the people who are generally not contented with their lives, and so cultivated this 'attitude'. This change of attitude may not necessarily be for the worse. They could have met someone who changed their attitude to the better, perhaps in life or in behaviour.
This is especially true for teenage girls. Somehow, girls are perceived as being more inclined to change. This could be due to our natural strive for perfection. We then find ourselves constantly wanting to conform and conform towards our peers, society and the rest of the world.
We call this the 'mid-life crisis'. This could be a change in belief, change in attitude or change in lifestyle. Belief, especially, is rather popular. They feel that they have to believe in something firmly and stick to it for the rest of their living time, be it a religion or a value, and eventually find the meaning of life through this belief.
A change in lifestyle is especially popular among the elderly. They realize they could not walk as fast anymore, do regular activities as easily anymore, or communicate as well anymore. They choose to slow down in their pace and really relax and watch the world go by. They take casual slow walks in the park, grocery shop in the wet market and socialize more with their age group.
How to cope with it
You've realized your friend or a close family member has somewhat changed, perhaps drastically or gradually, but you're not liking this change. Just take a step back and look at the situation in another perspective. They could have become someone better but you're just not used to it. In this case, give yourself some time, if you know he/she is becoming a better person in whole, accept it and support. Remember, those who matter don't mind and those who mind don't matter.
If you think they've changed for the worse, or at least in your point of view, find out if they're really happy about the way their lives are right now. If they are, that's all of your 'responsibilities' now. If they're not, offer to give them help. Some of them may not know or may not admit that they're not happy. In this case, make them notice themselves, which is the only way they will learn as time passes.
I hope the above points have helped you in some way or another. Comment down below about your experience with change!