It's funny yet sad that people can change drastically in a short time. 

From something to nothing. From nobody to somebody. From stranger to "best friend forever".
How can it be like that? how can people that first said "OMG this is totally my second family blablabla" and work so hard to be part of "that second family" then couple months later said "i don't care" and suddenly, it's not "the second family" anymore.So what is the point of struggling so much to be part of "the second family"

Just tell me, how can a person change his/her mind so drastically?

PS : pardon me for my bad grammar, rarely use english these days