Friendship ?

Wat truly defines friendship ? Wat I saw was juz ppl come stayed awhile in my life and they left, some I thought they will be on my side when others go against me but in the end they chose to be on their side and doubted me, some I thought I could be myself when i'm wif them but I came to found out tat actually they judged me and tok behind my back, some I thought we could be best friends for a lifetime, but in the end when they r better off and found new best friend they juz silently step out of my life, some I thought I knew them, but in the end I found out tat thr were so many things tat were happening to them tat I actually didn't noe and some I thought I was close to them bcoz I shared my personal stuff wif them, but in the end they can't even trust me enough wif their personal stuff. 

Sometimes I really wonder to them whr do I really stand ? I juz feel so pathetic tat my friendships r lyk tis, and I am someone hu really cherish friendships, if I bother to show my care and concern it really means tat u mean sth to me and I juz wan to be thr for u, but sometimes I wonder y should I even care when ppl dun trust me or might not even bother bout me. 

Is thr really such thing as true friendships? It juz seems so shallow and far fetched ..