So this offender is given a different sentence than someone else would have received simply because his wife pleaded for him? She did not commit the offense or was not the direct victim of the crime. If, instead, she was angry with her husband or decided to testify against him then he would have been sentenced differently.
How is this possibly justifiable?
That’s the whole reason you hear testimony from not only the family members of victims but family members of the newly convicted during sentencing. This is nothing new. If such testimony (on either side) carried no weight, we could dispense with that whole phase of the trial.