I believe it could often be due to character and personality differences ; unless two persons are rivals in a competition or have ulterior motives. In most cases we should try to compromise unless we are dealing with dangerous persons.
But friends are those that scolds us if we take the wrong path. There are times when we do not see our own faults and short comings.
Sometimes our own mind could be our greatest enemy. How do we deal with such a mind? perhaps we have to set rules for it and keep it busy.