Nici eu nu ma pot considera experta, insa iti pot spune ce greseli am remarcat.
Nu 'hardly thing' ci 'hardest things'.
Nu 'however much...'.Eu cred ca merge mai bine ' No matter how much time you have been having a very good relationship with a person called "best friend". Sooner or later this person may let you down.'
Sper ca te-am ajutat
Nu "hardly", ci "hardest".
In loc de "for a true friendship is necessary" - "for a true friendship it is necessary".
In loc de "However[...]" poti folosi "No matter how good a realtion with a person is, I think sooner or later this person will let you down".