Ok this is at number one for so many reasons.

The first reason is you can't force someone to fall in love with you.

The second reason if the love spell wears off then the person you loved will feel used and not loved.

The third reason is you should never play with peoples emotions it can hurt them emotionally, they can also feel betrayed by you.

The Fourth reason is the person you love won't feel real love only forced love, take Tom (Lord Voldemort) from Harry Potter as an example, the reason why he feel love is because his mom got pregnant with him from a love potion, and ever since he was born he could never feel real love.

The fifth reason why you should Never use a Love Spell on someone is that if they don't feel the same way you feel about them move on there are other fish in the sea.

The sixth reason is that love is something you can't force on someone you have to earn it.

The seventh reason not to use a love is the most obvious reason it dangerous and you can get hurt from it.

So that's why you NEVER EVER use a Love Spell