As long as the love spell wasn't aimed at a target then its not aganst anyones free will. It'll for example cause potential lovers to notice one or cause those who have feelings for the one who cast the spell to become confident enough to let them know.
But if it is targeted it may have a bad karma attachment or may backfire or cause the person to struggle with their emotions espicially if they know they don't really have feelings for you then it'll make them hate or cause them to go against you because their will is still there you would just be going against it.
As long as it's not targeted then you should be fine and love spells work a bit faster because your emotion and will are more intensified!
I guess thats true for any spell you get what you put in.