A win against Brighton would have improved Arsenal's title fight with Manchester City, but Arsenal's 3-0 defeat against Brighton meant that Manchester City went well ahead of Arsenal on points.
Arsenal are 4 points behind Manchester City after playing one more match. If they had won against Brighton, Arsenal would have had 84 points and Manchester City would have had 85 points, that is, the two teams would have been equally ahead in the title fight, but it did not happen.
Manchester City may be going for the league title along with the Champions League title this season.
Arsenal must give up the EPL championship this season to Manchester City, because Manchester City has a goal of getting a treble winner this season as well as chasing the FA Championship by beating Manchester United and CL also beating Inter Milan, only a few matches will determine whether they succeed in treble winners or not.
But as far as I see Intermilan is not something that is difficult following also the EPL in this season I am sure that Manchester City will clean up the remaining games at the end of the season with a win, Manchester United is a tough opponent for Manchester City in the FA but we will see, Guardiola is smart coach he can make another strategy to beat Manchester united in the FA.