Lol, quite a problem, well i will devise some plans:
There, do the "Love Spell" you want to use, taking away ones own free will is neither good nor evil anyway, it's just the human mind that make it good and evil, so do as you please, if you dont want Karma to backfire you.. well i think you should let go of your conscience while casting the spell, if you showed sympathy, it will definitely backfire.
Use the natural way, be a gentleman, have the qualities of being a gentleman, refine your attitudes, make the girl like you by showing her that you are a gentleman and a reliable person, some girls dont always look at the outer appearance of men, they also look in; Money, Protection you can provide them, Financial Support.
Those are the things i know so far some women look into men (ever notice why in T.V you often see gorgeous girls being married to a friggin' rich man albeit her husband looks like a bloated gas bag who also looks like a gorilla)?
If Plan A and B fails, Hypnotize her, study Psionics dude.
If Everything else fails, then go find a new girl, dude, there are millions of girls in this planet, would be better if you find a job that also has something to do with going on different places in the world.
Well those are the plans i can think of lol, well i havent experience falling in love before though so i dunno if plan B is still applicable, because...well i still dont have a girlfriend yet (im 16 now and 2nd year college student) the main reason is im a very picky guy, all of the girls in this city... just dont possess the qualities of the girl I like lol XD So im planning on finding one when i already have a job, besides I enjoy spending my allowance on Online Games than spending them to date a Girlfriend haha, and also i have a lot of things to do, so having a girlfriend just eats up my time for more important things, single life is fun dude, and being single is the Plan E.
The only requirements for Plan E is observe the girl you like and then think of all of her flaws, let those flaws turn you off, and there, the fire of love has been extinguished and welcome single life hahaha XD