It interferes with "free will". The woman I dealt with was an actual practicing wiccan and heavily into. She was a friend.
We played around with it on one man. Least it to say, he reacted one day hostily. He was not the type for it then stopped and said, " I do not know what is going on. "
When I was younger with her assistance I placed a spell on one person to test it. He reported back to us... all of sudden he started screaching for the person obsessively and did not know what came over him.
Said he thought spells were hogwash till that happen and found out what we did.
Online spells are not trust worthy with some of these people.
If you want a spell done. Research it yourself, do not trust "online spells". Get the right book, make the right contacts and test it out for yourself.
You will spend way less, also.