Hmm... How about this timeline?

Nigel's men starts harassing Isaac, Hayley and Sean -> Kill Sarah -> Arlia and Nigel bond further -> Hayley found out about Isaac's past and leaves in rage -> Nigel finds out fucked up shit about Arlia -> Nigel rescues Arlia -> Hayley and Isaac sort their shit out and reunite -> Nigel and Arlia join forces with Isaac, Hayley and Sean -> Nigel remembers about Hayley and tries to sort their shit out