Sarah is heartless
Think about a typical pet owner, especially in USA.
The tiniest dogs are dressed up as 'cute kids', they are given extravagant birthday parties and all the toys they can ever chew up - of course the dogs are and from all that, become psychologically imbalanced, but as this doesn't affect the 'cuteness', the owners don't care unless the dog starts exhibiting this imbalance in 'harmful' ways, like destroying the house or biting other people or dogs.
In any case, these pet owners LOOOOOOOOOOOOOOOOOOOVE their little pets, no matter what the pets are. Tarantula owners would never leave their tarantula on their own and not care about them suddenly, even IF a robot from the future comes to try to kill them.
What about Pugsley?
Sarah supposedly loves this lizard so much she kisses it and cuddles with it (sort of), but suddenly, she COMPLETELY forgets about it!
What kind of sense does this make? Pet owners here, would YOU forget about your pet just because some Austrian Bodybuilder-looking robot came from the future to try to kill you?
WOULD YOU??
Sarah is absolutely heartless - she just ABANDONS her pet that now has to just try to live in that apartment alone... and slowly dies a horrible death.
Damn Sarah.. how can you be so heartless to a pet you supposedly love so much you can kiss a lizard?