Come and Go

Haven't been constantly sure about what's ahead of my life. But change is ever constant.
I meet new people almost every week when I'm out to socialize, and I lose some along the way.
People come and go, but who's to stay?
I've been wondering - why has the person who was so determined to leave me before, trying so hard to restore it's situation now?
Should you have known how much you wanted that person to stay in your life then, what made you so sure when you decided to leave?
Something that I'd really wanna know but I guess I wouldn't ask. Cause if those people successfully come back and stay in my life, one fine day in our conversations, we will mention it.
However if we remained strangers, then I guess there isn't a need for me to know why you truly left me for.
I cherish every new friend I make, and I hope they know the value of an acquittance which might become something for the better, in time.