Why does Mal insist on communal suicide in Inception? If they were really still dreaming, she could just die alone and kick Cobb on the level above (if death would wake them up, it means there are no synchronized kicks needed). Murder-suicide would be another option. From her point of view, this would amount to helping a deluded person and her solo suicide as negligence.
Of course, she ends up committing solo suicide, but before that, she first spent weeks/month (?) trying to persuade Cobb and then executed an elaborate scheme that involved having three psychiatrists declare her sane and wrecking a hotel room. The alternatives would have been much easier. Her instinctual resistance to killing her husband would probably have been weakened, because she already did it multiple times during their boundless dream-exploration.
In my view, her focus on communal suicide points more to mental illness as opposed to actually believing they need to wake up.