He wasn't married when he was elected and became one of only three presidents who got married after they won the election and he was the only one who got married in the White House. He ended up with five children and several pets in the house. What's also interesting about Cleveland is he liked to answer the White House phone himself.
Cleveland disliked showing special favors to any group. When a bill was passed granting aid to drought-stricken farmers in Texas, Cleveland vetoed it because he thought such aid fostered an expectation of “paternal care” by the government and “weakened our national character.” Things have certainly changed as government aid is a constant now and a way of buying votes.
His hard stances made it to where members of both parties had problems with him. Leaders of the Democratic Party told Grover that he probably wouldn't be re-elected because he didn't know how to play the game, to which he said: “What is the use of being elected or re-elected unless you stand for something?” They were right, he lost in 1888; but amazingly he won again in 1892. He's still the only president to serve two non-consecutive terms. What's funny is that Frances Cleveland told the staff at the White House to take care and that she'll see them again in four years. She was a visionary. :)
President Cleveland discovered a growth on the roof of his mouth that was assumed to be cancerous. In order to not panic the pubic, he snuck aboard a boat over a Fourth of July holiday. Doctors were already on board waiting to perform surgery. Except for a select few, no one knew where he was for five days. It was such a well kept secret that news of his illness and surgery wasn't revealed until nine years after his death.