In the general, modern sense, witchcraft has no central authority. There is no agreed-upon scripture or doctrine. Which is both the difficulty and the beauty of it. Practitioners are free to create their own unique practice.
Of course, that also means they are responsible for their own practice, and the results of that practice.
The practitioner is expected to come up with his/her own moral and ethical code. She/he must decide for themselves whether a love spell is unethical, or even if they believes it will work. She/he has to make up their own mind about big, heady things like whether or not they believe in god, or if it’s okay for them to continue to practice spellcraft alongside Christianity.