While I don't agree with the sentence, it does appear to be consensual sex, which may have had an impact, and the following snippet from the article gives more details:
Hillsborough Circuit Judge Wayne Timmerman said LaFave also will forever lose her teaching certificate, must register with the state as a sexual predator, may not have any contact with children including the victim, and will not be allowed to profit from the sale of her story or personal appearances.
The victim's mother said afterward that the public scrutiny had taken its toll on the family, and they just wanted to see it all end.
"If we had continued along this path, this would have followed him forever," said the mother, whose name was being withheld to protect her son's identity. "My prayer is that he can leave this behind him and go on and be a happy, healthy young man."