Zombies are not bound by anything.  It's a rarity  for them to make a commitment, now that's not to say they are immune to a little romance now and then, they are however, notoriously unreliable.  When a zombie is determined to do something (eat you), it's gonna 'git'er done'. Might be as soon as today, could be tomorrow.  Zombies are mysterious and serve their own purpose.

 

And then the man of steel's great need came upon him.  He was suddenly on fire with out of control emotion.  A chaos of feelings swept over him tightening into a shattering joy as he thrust forward in pleasure grasping the skintight old-lady's vertebrae one by one with a thrust so vehement it knocked his legs out from under him  and he was on fire, chittering and snorting in a delirium of joy.  The old lady thought he was pretty hot too.