its a personal thing. most people join SoM or pagan paths for the sole purpose of love spells. as a result most people think 'it's love. love is good, i'm not physically harming the person.' they don't go past the physical. mentally and emotionally you have a hold on this person, you are fulfilling your desire by impairing theirs. they may seem happy, and might feel happy, but they are not truly happy. a love spell is an illusion, like you hypnotised the person. you cannot trust this form of love.
spells to attract more love into your life, or get someone who already loves you to ask you out is another matter, you are not forcing your will over their will, you are either asking the universe for help or a nudge in the right direction.
this is all personal views and opinions however, some could probably argue curses are necessary. it's all personal morality.