I am in terms of boyfriends and girlfriends. And you dump someone only to regret it later on. Why can't you appreciate what you have? Do you believe that if they truly cared they would never have dumped you?
When we are young we don't fully realize what we do and the consequences behind it. It's like your mother telling you not to ride on the handlebars and you do anyway until you actually get thrown off. Then reality hits and you realize there was a reason why she said it. We as people are generally blind to reality until it hits close to home. We think we can do just as good if not better with someone else, then we realize that no one else can make you feel the same way. With age comes wisdom, and with wisdom comes being careful of our actions and feelings.
This is a question asking about psychiatric decision making.
In my observations of people I've noticed that they are very selfish, that leads them to want better things. THAT in turn leads to breaking up in pursuit of something better, regardless of how happy you were/are. People are illogical, and this will ALWAYS happen.
I don't think it's really a matter of how much someone cares, its just that people get comfortable/used to what they have around them. For example, if you're in a long term relationship, it doesn't work out, and you guys break up, you have good reasons to break up, but a few weeks/months later, you regret it because you miss having someone around, the memories, etc. During this time is when you realize all the good things and push the negatives aside, and to me that's when people realize what they've lost.
This isn't for all people, of course there are the ones who recognize all the good stuff DURING the realationship, but I'm sure everyone will come across a situation like this. Appreciate as much as you can, and if it dosen't work out, then you can't say you didn't appreciate.
You can't appreciate what you have until it's gone because you don't realize how big of a role they played in you're life. If they dump you, they can truly care for you. They may have been doing it for simple reasons such as they know you can do much better than them, or maybe because there was something was missing in the relationship. They can always truly care about you, but maybe not love you like they way you want them to.