Liverpool are hard to beat at Anfield especially when they are in great form... although sometimes Newcastle put up a fight but they are not consistent enough...
Try to imagine if Arsenal lose to Forest and Liverpool win then the difference in points will be far then difficult to catch up with Liverpool ... as well as the potential title is getting closer.
Arsenal did not show their potentiality to play better, perform more consistently to catch Liverpool. It's their main first target to achieve but with their inconsistency, it's nearly impossible. Their competitor Liverpool, like you said, are simply stronger and more stable, so they will continue playing well and not only maintain 8 point difference with Arsenal but also wait for chances to expand it bigger and bigger.
The season is counting down very last matches till the end, and each good match with three points will bring Liverpool nearer to Premier League trophy. Arsenal with each bad match will give Liverpool extra help to win the title earlier than the final match day of season.