Love Spells

Hi
I have followed the wiccan path for a while but am starting to have doubts here about what I am playing with. I did a spell to attract love. I wrote down all the attributes of a man I wanted and I dated him this man for a while. At first he seemed really charming, really nice but he soon turned controlling, nasty and abusive. I have been reading around about love spells and some people suggest that they are not particularly "ethical". I know if you specifically want someone in particular and do a spell you are changing their free will and can get negative karma come back on you times 3 but if you just did a spell to attract love and not a particular person why would you get negative karma come back at you?
Some say you shouldn't do spells for selfish reasons. However loads of people do love spells don't they? Can someone shed some light on this please?