you dont need to be worried because even if arsenal had won the game i dont think they will be able to meet up liverpool in points, liverpool is more consistent in premier league this season than every other teams, their perfomance this season is good to tell they will be the champion. i dont expect arsenal to lose by this time because they are far behind to get to the top of the league, butim not surprise abvout arsnal losing the game because they are fond of losing games like this in a critical time like this when they really need some points. arsenal are doing well but i dont think they are in the best perform to win the league title because they always compromise in their games sometimes.
Arsenal can not win against Liverpool in Premier League title race but defeat like this is generally not good for them. They finished two latest seasons with a runner-up position and are going to have it again. At least they don't want to fall to a third position because it does not show their improvement in this season at all.
If Arsenal can hold a runner-up position at the season ending, they will have belief that if they don't improve themselves too much, at least they don't become a worse version of themselves compares to two latest seasons. In addition, Arsenal are still playing in Champions League and they will need good form in Premier League as preparation for Champions League round of 16 matches with PSV too.