I dont know how you play so dont take this offensively, but you also need to check how YOURE playing. Aggro management is not just the tanks job.

Thats an AOE rotation, does she use something different for single target?

Rune strike is a proc that she can use when she dodges / parries for threat gain so that should definitely help if shes not using it.

For single target depending on how she is playing we should see either death strike (for healing), obliterate or scourge strike. Those are the big hitters.