Why were greek poli unhappy with athens in the years preceding the peloponnesian war

As a consequence of the Persian war, Athens had dominance over the Delian League and military alliance to prevent another attack. That means that they had a strong naval force, as well as the money from the league that they used for their gain, not giving it up to the poli. They also had the dominance to dictate the customs and bans on trade.

Many of the poli were unhappy with this state of things and thought that Athens had too much power. Sparta held the most resentment. It was exactly Sparta that started to gather other poli to stand up against Athens, which was the beginning of the Peloponnesian war.