The promoted side were made to play with ten men for the final half-hour of the contest after Nathan Ake was sent off in what Flores believes was a positive showing.
"The line separating wins and losses is very thin - one minute we can win the match, one minute later we lost," Watford head coach Flores said.
"I am proud of the players because they fight a lot. They have a very big soul.
"They have amazing desire to play for the fans against a very tough team but the first feeling of course is sad because we are really close to taking one point against an amazing team."